3D Printing 101, Part 4: The Ultimate Materials Deep Dive. Filaments, Resins, and When to Use What

Part 3 covered your printer settings: layer height, infill, supports, and all the slicing decisions that turn a model into a print. Good settings matter. But settings can only work with what you give them. Feed the wrong material into your printer and no amount of tuning will save you.

This is the part where the machine stops being the main character. The material takes over.

Every filament and resin has a personality. Some are forgiving and friendly. Some are stubborn, demanding, and will warp off the bed at 3am just to spite you. Understanding those personalities before you load a spool is the difference between a clean, functional print and a birds-nest disaster you have to scrape off the build plate with a spatula.

Part 4 is the full materials picture: FDM filaments from PLA to TPU, resin types for SLA and MSLA printers, and honest recommendations for where to start and where to go next. No gatekeeping. No jargon walls. Just the information you actually need.

Why Materials Matter More Than You Think

A skilled woodworker doesn't reach for whatever's closest. Pine is cheap and easy to cut, perfect for rough shelving. Oak is dense and durable, built for furniture that lasts generations. Balsa is almost weightless, ideal for models and props. None of them is universally "best." Each one is right for something specific.

3D printing materials work exactly the same way. The choice affects everything: how strong the part is, whether it flexes or snaps, how much detail it can hold, how the surface looks, and whether your printer can even produce it reliably. A material that's perfect for a decorative figurine might crack under mechanical stress. A material that handles heat beautifully might require an enclosure, a specific bed temperature, and ventilation.

The "just use PLA" trap

PLA is the standard recommendation for beginners, and it earns that status. It's forgiving, widely available, and works well on almost any FDM printer. But "just use PLA" becomes a trap when people stop there. Some makers print PLA for years without realizing that a different material would solve the exact problem they've been working around: a part that keeps breaking, a print that warps in a warm car, a flexible component that needs to bend without cracking.

How the wrong material can ruin a perfectly good print

Material mismatches don't always produce obvious failures. Sometimes the print looks perfect and fails three weeks later. A PLA bracket installed near a car's interior can soften and deform on a hot summer day. An ABS print attempted without an enclosure can delaminate between layers, looking structurally fine until it isn't. A flexible phone case printed in standard PLA will crack on the first drop. The geometry was right. The settings were dialed. The material was simply wrong for the job.

Understanding the full materials landscape means you choose intentionally, not by default. That's what this guide is for.

FDM Filament Fundamentals: What's Actually Inside That Spool

How filament is made and why it matters

FDM filament starts as raw thermoplastic pellets. Those pellets get melted down, extruded through a precision die into a continuous strand, cooled in a water bath, and wound onto a spool. The result is what you load into your printer: a long, consistent strand of plastic that your hotend melts and deposits layer by layer.

The word "consistent" is doing a lot of work in that sentence. Diameter consistency is one of the most important quality factors in filament, and it varies dramatically between manufacturers. A spool that fluctuates between 1.70mm and 1.80mm will cause uneven extrusion, visible in your prints as irregular surfaces and weak spots. Good filament holds tolerances within ±0.02mm or tighter.

Diameter, quality, and storage basics

The two standard diameters are 1.75mm and 2.85mm. The FlashForge Inventor uses 1.75mm, which is by far the more common standard across consumer FDM printers. If you're shopping for filament, 1.75mm is almost certainly what you need.

Beyond diameter, moisture content is the variable most beginners overlook. Many common filaments are hygroscopic, meaning they actively absorb moisture from the surrounding air. PLA, PETG, Nylon, and TPU are all hygroscopic to varying degrees. Wet filament pops, hisses, and steams during printing. It produces rough, bubbly surfaces and dramatically weakened layer adhesion.

The fix is straightforward: store filament in sealed bags with desiccant packs, or invest in a dedicated dry box that keeps humidity below 15%. Once filament is wet, a filament dryer can recover it in most cases. Prevention is easier than recovery.

PLA: The Crowd Favorite (And Why It Deserves the Hype)

What makes PLA beginner-friendly

PLA stands for Polylactic Acid. It's a biodegradable thermoplastic derived from plant starches, typically corn or sugarcane, which makes it one of the more environmentally friendly options in the filament lineup. That backstory is interesting, but the reason everyone starts with PLA is simpler: it's the easiest filament to print successfully.

Print temperatures sit comfortably between 190 and 220°C. A heated bed helps with adhesion but isn't strictly required. Warping is minimal compared to almost every other filament. It produces very little odor. It's compatible with virtually every FDM printer on the market, including the FlashForge Inventor, which lists PLA as its primary recommended starting material.

For decorative prints, cosplay props, prototypes, and household objects that won't face heat or heavy mechanical stress, PLA is genuinely excellent. The surface detail is good. The color range from most manufacturers is enormous. It's cheap, widely available, and forgiving of imperfect settings.

PLA's real weaknesses. No, it's not perfect

The glass transition temperature of standard PLA sits around 60°C. That sounds fine until you leave a PLA print in a car on a summer afternoon and come back to a warped puddle. It's brittle under sharp impact compared to PETG or ABS. It degrades with prolonged UV exposure and absorbs moisture over time, which matters for anything meant to last outdoors.

These aren't dealbreakers. They're just honest constraints. A PLA figurine sitting on a shelf is fine forever. A PLA bracket inside an engine compartment is a bad idea from the start.

PLA variants: Silk, Matte, PLA+, and beyond

The base PLA formula has spawned a useful family of variants.

PLA+ adds modifiers that improve impact resistance and introduce a slight flexibility compared to standard PLA. It prints at similar temperatures and is a direct upgrade for functional parts where standard PLA tends to crack.

Silk PLA incorporates additives that produce a glossy, almost metallic sheen. It's visually striking and ideal for display pieces, busts, and decorative objects. It's slightly more brittle than standard PLA and not meant for structural use, but for anything meant to look impressive on a shelf, it's hard to beat.

Matte PLA goes the other direction: a flat, low-sheen finish that hides layer lines better than any other PLA variant. If you're printing something that you want to look less "3D printed," matte PLA does more work before post-processing than anything else in this price range.

All three variants print on the same temperature range as standard PLA and work well on the FlashForge Inventor without any special configuration.

ABS: The Tough Old-Timer With a Bad Reputation

ABS stands for Acrylonitrile Butadiene Styrene. You've been handling it your whole life without knowing it. LEGO bricks are ABS. Car dashboards are ABS. Countless appliance housings and electronic enclosures are ABS. It's a proven industrial material with a long track record, and it earned its place in the FDM world for good reasons.

Where ABS still wins

The heat resistance is the headline advantage. ABS starts to soften around 100°C, which is nearly 40 degrees higher than standard PLA. For parts that live in warm environments, that gap is significant. ABS is also tougher under impact, less brittle than PLA, and it machines and sands well. The most compelling post-processing trick in FDM printing is acetone smoothing: exposing ABS prints to acetone vapor partially dissolves the surface layer, fusing the layer lines into a smooth, near-injection-molded finish. No other common filament offers that.

Why ABS is unforgiving and how to tame it

The challenges are real. ABS warps aggressively. As it cools unevenly, layers contract at different rates, pulling the print away from the bed and sometimes causing full delamination between layers. Printing ABS without an enclosure is asking for trouble. You need a heated bed at 100 to 110°C, an enclosed build chamber to maintain ambient temperature, and ventilation because ABS releases styrene fumes during printing. Styrene isn't something you want to breathe in an unventilated room.

The FlashForge Inventor's enclosed build chamber gives it a meaningful advantage here. The enclosure traps heat and stabilizes the ambient temperature around the print, which is exactly what ABS needs to stay adhered and avoid delamination.

ASA: the weather-resistant upgrade

ASA (Acrylonitrile Styrene Acrylate) is what ABS wants to be when it grows up. It shares ABS's heat resistance and impact toughness, prints at similar temperatures, and adds genuine UV resistance that ABS lacks. For anything destined to live outdoors, ASA is the better choice. It's slightly easier to print than ABS in most setups and doesn't yellow or degrade under prolonged sun exposure. If you're printing garden fixtures, outdoor enclosures, or automotive exterior parts, ASA is the material to reach for.

PETG: The Sweet Spot Nobody Talks About Enough

PETG properties and why it bridges PLA and ABS

PETG stands for Polyethylene Terephthalate Glycol. The "G" distinguishes it from standard PET, the plastic used in water bottles, with a glycol modification that makes it easier to process and less brittle. The result is a filament that sits in a genuinely useful middle ground between PLA and ABS.

Heat resistance lands around 80°C, a solid 20 degrees above PLA. It's tougher and more flexible than PLA, meaning it absorbs impact rather than cracking. Layer adhesion is excellent, often better than PLA. Warping is minimal. Food-safe versions exist from certain manufacturers, though the layer lines in FDM prints create crevices that are difficult to sanitize properly, so "food-safe filament" and "food-safe print" aren't automatically the same thing.

The print temperature range is 230 to 250°C at the nozzle and 70 to 85°C at the bed. Those numbers are higher than PLA but still well within the range of most consumer printers. The FlashForge Inventor handles PETG without any modifications.

Common PETG printing pitfalls and how to solve them

PETG has one notorious quirk: it strings. Thin wisps of plastic appear between separated parts of a print, like a spider built a web inside your model. Tuning retraction settings reduces this considerably, and a slightly lower print temperature helps too. It takes a few test prints to dial in, but it's solvable.

The second quirk is almost the opposite problem: PETG adheres to build surfaces aggressively. Too aggressively. It can bond so firmly that removing the print damages the surface or the print itself. A thin layer of glue stick or a dedicated release agent on the bed surface creates a barrier that lets the print release cleanly without fighting it.

PETG is also slightly more moisture-sensitive than PLA. Not as dramatic as Nylon, but wet PETG strings worse and produces weaker prints. Sealed storage with desiccant is worth the habit.

If you've mastered PLA and you're wondering what to try next, PETG is the answer. It solves the most common PLA limitations without introducing the complexity of ABS.

TPU and Flexible Filaments: Printing Rubber-Like Parts

What TPU is and what it can do

TPU stands for Thermoplastic Polyurethane. It's the filament that lets you print parts that behave like rubber: flexible, compressible, and resilient. Standard thermoplastics snap or crack when bent repeatedly. TPU bounces back.

The applications are specific but genuinely hard to replicate with any other material. Phone cases, gaskets, seals, grip covers, vibration dampeners, shoe insoles, protective bumpers, wearable components. Anything that needs to flex, absorb shock, or create a friction surface is a candidate for TPU.

TPU also has excellent abrasion resistance and reasonable chemical resistance, which makes it suitable for parts that see regular wear or exposure to oils and mild solvents.

Shore hardness is the rating system for TPU flexibility. An 85A Shore rating is quite soft and pliable, close to a rubber eraser. A 95A Shore rating is firmer, more like a hard shoe sole. Softer grades are better for gaskets and grips. Firmer grades work better for structural flexible parts that need to hold shape under load.

The challenges of printing flexible filament

Printing TPU is like trying to push a cooked noodle through a straw. The material's flexibility, which makes it so useful in the final part, works against you during extrusion. Push too fast and the filament buckles inside the extruder path instead of feeding forward.

The solution is patience. Print speeds of 20 to 30mm/s are standard for TPU, well below the speeds you'd use for PLA or PETG. Retraction should be minimal or disabled entirely, because aggressive retraction pulls the soft filament back unevenly and causes jams. Dry filament is critical: wet TPU strings badly and loses its mechanical properties noticeably.

Direct drive extruders handle TPU far better than Bowden setups. In a direct drive configuration, the extruder motor sits directly above the hotend, minimizing the distance the filament travels before being melted. Bowden setups

Specialty and Engineering Filaments: When You Need More

PLA gets you started. PETG gets you functional. But eventually, a project lands in your lap that neither one can handle. Maybe you're printing a bracket that lives under a car hood. Maybe you need a part that flexes ten thousand times without cracking. That's where engineering-grade filaments enter the picture, and they don't mess around.

Nylon: Strong, Flexible, and Frustrating

Nylon is one of the most capable materials you can run through an FDM printer. It's genuinely strong, absorbs impact well, and handles fatigue cycles that would shatter PLA in a week. Gears, hinges, snap-fit clips, load-bearing brackets: Nylon handles all of it without complaint.

The catch is everything else about it.

Nylon is extremely hygroscopic, meaning it absorbs moisture from the air faster than almost any other filament. A spool left out overnight in a humid room can become unprintable by morning. You'll see bubbling, stringing, and weak layer adhesion. It also warps aggressively, demands print temperatures above 240°C, and really wants a fully enclosed printer to retain heat. The FlashForge Inventor can handle Nylon in controlled conditions, but plan on a learning curve.

Carbon Fiber Composites: Lightweight and Stiff

Carbon fiber filaments (PLA-CF, PETG-CF, Nylon-CF) aren't pure carbon fiber. They're a base material infused with short chopped carbon fiber strands. The result is dramatically stiffer and lighter than the base material alone, which makes them excellent for structural parts where weight matters: drone frames, camera mounts, tool handles, aerospace mockups.

The trade-off is abrasion. Carbon fiber is hard, and it will chew through a brass nozzle in hours. You need a hardened steel nozzle before you run a single meter of CF filament. That's a $15 upgrade, but skipping it is an expensive mistake.

Other Specialty Materials Worth Knowing

Polycarbonate (PC) sits at the top of the heat-resistance ladder among common FDM filaments, tolerating temperatures between 110°C and 130°C before deforming. It's nearly transparent in thin sections and genuinely tough. It's also the most demanding material on this list: print temperatures of 260°C to 310°C, a fully enclosed chamber, and a heated bed above 100°C. Most stock printers can't run it without modifications.

Wood, metal, and glow-in-the-dark filaments are composites built for aesthetics, not engineering. Wood-fill and metal-fill filaments produce beautiful surface textures and can be sanded, stained, or polished. They're also abrasive. Glow-in-the-dark filaments are surprisingly popular for cosplay and display pieces. None of these are structural choices.

The honest framing here: engineering filaments are for intermediate to advanced users. If you're still dialing in your first PETG print, bookmark this section and come back later. Master the basics first. The specialty materials will still be here.

Resin Printing Materials: A Completely Different World

Everything you know about filament doesn't apply here. Resin printing operates on a completely different physical principle, produces completely different results, and demands a completely different mindset about safety. It's not harder or easier than FDM. It's just different, and it's worth understanding on its own terms.

How Resin Works vs Filament

FDM printers melt solid plastic and deposit it layer by layer. Resin printers do the opposite: they start with a vat of liquid photopolymer resin and cure it solid using UV light, one layer at a time. The Anycubic Photon S uses MSLA (Masked Stereolithography) technology, where an LCD screen masks a UV light source to expose only the precise cross-section of each layer.

The practical result is resolution that FDM simply can't match. Where FDM layer lines are measured in tenths of a millimeter, resin printers routinely achieve layer heights of 0.05mm or less. The surface finish comes out smooth enough that you can skip sanding entirely on many prints.

"Resin printing doesn't replace filament printing. It completes it. The two technologies solve different problems, and understanding that distinction is what separates a hobbyist from someone who actually gets things done."

Standard Resin: The PLA Equivalent of the Resin World

Standard resin is where almost every resin printer owner starts, and for good reason. It's affordable, widely available, prints reliably on the Photon S, and produces stunning detail. Miniatures, jewelry masters, figurines, display pieces: standard resin handles them beautifully.

The weakness is brittleness. Standard resin cures hard but snaps under stress. Drop a standard resin print from waist height onto a hard floor and you'll find out exactly how brittle it is. For anything that needs to survive real-world handling, it's not the right call.

Safety is non-negotiable here. All liquid resin is toxic. Uncured resin irritates skin, damages eyes, and produces fumes that accumulate in enclosed spaces. Gloves, a properly fitted respirator, and ventilation aren't optional precautions. They're the baseline every time you open a bottle.

ABS-Like Resin: Tougher and More Functional

ABS-like resin is the upgrade most resin users make after their first few months. It retains the high detail of standard resin but adds meaningful toughness and a slight flexibility that prevents catastrophic brittle failure. It's not as tough as actual ABS filament, but it's significantly more functional than standard resin.

For the Photon S specifically, ABS-like resin is the best choice when you want prints that can be handled, assembled, or lightly stressed. Enclosure parts, cosplay accessories, snap-fit components: ABS-like resin handles the job. Anycubic's own ABS-like resin is a reliable starting point because the exposure settings are pre-tuned for Photon S hardware.

Flexible and Specialty Resins

Flexible resin cures to a rubber-like consistency. It can be printed straight or blended with standard resin in varying ratios to dial in a custom Shore hardness. Gaskets, wearable parts, figurine bases that won't crack when they tip over: flexible resin solves problems nothing else can.

Water-washable resin swaps the standard isopropyl alcohol wash step for plain water, which makes cleanup dramatically easier. The trade-off is slightly reduced durability compared to standard resin. For beginners who want to skip the IPA handling, it's a fair trade.

Beyond those, the catalog expands into niche territory. Castable resin burns out cleanly in a kiln, making it the material of choice for lost-wax jewelry casting. Engineering and dental resins hit performance specifications that standard materials can't approach, but they cost significantly more and require precise calibration. They're tools for professional workflows, not weekend projects.

The Anycubic Photon S is compatible with virtually any 405nm MSLA resin. That covers most consumer resins on the market. When in doubt, start with Anycubic's own standard or ABS-like resin, nail your exposure settings, and branch out from there.

Head-to-Head: Resin vs Filament. Choosing the Right Tool

The question isn't which technology is better. That framing is wrong from the start. The real question is which technology is right for the specific thing you're trying to make, right now. Once you internalize that, the choice becomes straightforward.

When to Choose FDM (Filament)

FDM wins on size, speed, and material variety. If you're printing anything larger than roughly 130mm in any dimension, resin becomes impractical fast. If you need a functional part that handles mechanical stress, FDM filaments give you a far wider range of structural options. If you're printing in a space with children, pets, or limited ventilation, FDM is the safer choice by a significant margin.

Cost per print also favors FDM. A kilogram of PETG costs roughly $20 to $30 and produces a large volume of printed material. Resin is more expensive per milliliter and generates chemical waste that requires careful disposal.

When to Choose Resin

Resin wins on detail, surface finish, and precision at small scale. Tabletop miniatures, jewelry prototypes, dental models, cosplay accessories with fine surface texture: resin produces results that FDM can't replicate regardless of settings. If the surface of the print is the point, resin is the answer.

Can You Use Both? (Yes, and Here's How)

Owning both an FDM printer and a resin printer isn't redundancy. It's a complete toolkit.

Consider a custom prop weapon. The internal frame and handle core need strength and size: print those in PETG on the FlashForge Inventor. The decorative surface panels with fine engraved detail need resolution: print those in ABS-like resin on the Photon S. Bond them together, prime, paint. The result looks like it came from a professional shop.

That hybrid workflow is available to anyone running both machines. Design once in CAD, split the model by function, assign each component to the right printer, assemble the result. It takes more planning, but the output is genuinely better than either technology could produce alone.

Practical Material Recommendations: What to Actually Buy

The options are endless and the decision paralysis is real. Here's how to cut through it.

Beginner Starter Kit: Filament

Start with one kilogram of PLA from a reputable brand. eSUN, Hatchbox, and Polymaker all publish material data sheets, maintain consistent filament diameter, and have earned trust in the community over years of use. Avoid ultra-cheap no-name spools. The price difference between a $15 mystery spool and a $25 Polymaker spool is trivial. The difference in print quality and failure rate is not.

Once you've printed two or three successful PLA projects, buy a spool of PETG from the same brand. Same printer, same basic workflow, meaningfully better functional properties. That's the entire beginner filament journey.

Beginner Starter Kit: Resin

Start with 500ml of standard resin or water-washable resin from Anycubic. Neutral gray or beige colors show detail more clearly than opaque black or white, which helps you evaluate print quality during the learning phase. Anycubic's own resin is pre-calibrated for the Photon S, which removes one variable while you're still learning the others.

Match your printer manufacturer's resin first. Branch out once you know your machine.

Intermediate and Advanced Material Progression

After PLA and PETG are comfortable, add TPU for flexible prints and PETG-CF for stiff structural parts. On the resin side, add ABS-like resin to your shelf. Those three additions cover the vast majority of intermediate projects.

Advanced users with specific functional requirements can explore Nylon, PC, engineering resins, and castable resin. Each one solves a narrow problem exceptionally well. Buy them when you have a project that genuinely needs them, not before. Quality materials reduce failed prints, and failed prints are where the real money gets wasted.

Your Part 4 Action Checklist

Every item on that list takes less than 30 minutes total. Do them before Part 5 drops and you'll arrive with a clearer picture of your materials, your storage situation, and what you actually want to print next.

What's Coming in Part 5

You now know your materials. Part 5 puts them to work.

Next up is Printing Fundamentals: layer height, support structures, infill patterns and density, exposure settings for resin, and the calibration steps that turn a decent printer into a reliable one. Every setting in that article connects directly to the material you're printing. Nylon needs different layer heights than PLA. Flexible resin needs different exposure times than ABS-like. The material knowledge you built here isn't background context. It's the foundation every Part 5 decision sits on.

Before Part 5 publishes, print something small using what you learned today. Pick a material deliberately. Think about why it's the right choice for that specific object. Every expert in this hobby was once standing in front of a wall of filament colors feeling completely lost. The wall doesn't get smaller. You just get better at reading it.

See you in Part 5.