The Filament Buyer's Guide

Each material has relative 1–5 ratings for strength, stiffness, impact, layer adhesion, heat, flexibility, UV, chemicals, moisture and surface detail. They compare FDM filaments with each other — a 5 for strength is strong for a printed plastic, not for steel or injection-moulded parts.

Every number is cited. Most come from QIDI's own technical data, because those are the filaments and printers we use; where QIDI doesn't publish a value we cite another manufacturer's datasheet and say so. Datasheet values are measured on carefully printed test bars, so treat them as best-case and directional.

Nothing here is a guarantee of how your part will perform. Geometry, orientation, wall count, infill, colour and the environment change the outcome. Tell us how the part will be used and we'll recommend — or test — before production.

FDM parts are built from fused lines of plastic, layer on layer. They are strongest along the printed lines and weakest between layers, where the bond is only as good as the heat and pressure at that moment. QIDI's comparison guide lists XY bending strength alongside Z (between-layer) tensile strength for each filament, and the gap is large for every material.

That's why we orient parts so the main loads run along the layers, and why a clip, hook or thin post printed standing up can snap at a load that would barely flex it lying flat. Some finishes make this worse: QIDI's data shows one matte PLA with a fraction of the Z-strength of standard PLA.

If a part has a known load direction, tell us. It often matters more than switching to a stronger material.

Many filaments are hygroscopic — they absorb water from the air. Wet filament prints with bubbles, stringing and weak layers, and some materials keep absorbing water after printing. QIDI's guide lists saturated water absorption from about 0.05% for PETG to around 2% or more for nylons.

We dry moisture-sensitive materials before printing (the QIDI Box can dry at up to 65 °C, and higher-temperature materials are dried in a dedicated dryer). Drying is one reason engineering materials take longer and cost more.

For nylon parts, absorbed water changes the finished part too: it becomes tougher and more flexible, but less stiff, and dimensions can shift slightly. Each nylon page explains what to expect.

Fibre-filled filaments contain short chopped fibres, not continuous carbon fibre. They make parts stiffer, more dimensionally stable and less prone to warping, with an attractive matte finish. They usually don't make parts tougher; many become more brittle under impact.

Fibres are abrasive and wear out brass nozzles quickly. Both our printers ship with bimetal nozzles that QIDI lists as suitable for carbon- and glass-fibre filaments, and QIDI advises against 0.2 mm nozzles for fibre filaments — so very fine detail isn't available in these materials.

Carbon fibre and glass fibre behave differently: carbon is stiffer and lighter; glass is generally tougher, electrically non-conductive and less expensive. The composite pages compare them directly.

Materials like ABS, ASA, PC and nylon shrink as they cool. Without a warm, enclosed environment, corners lift and tall parts crack between layers. Both of our printers have an actively heated chamber that reaches 65 °C, which makes these materials practical to print reliably.

Low-temperature materials need the opposite: QIDI recommends keeping the chamber roughly 10 °C below a filament's softening point, which for PLA means no more than 45 °C. We set chamber temperature per material.

Even with a heated chamber, large flat parts and thick sections in engineering materials can warp or shrink slightly. If you have tight dimensions on a large part, flag them and we'll advise on orientation, ribs or splitting the part.

Sunlight attacks many plastics, causing fading, chalky surfaces and gradual embrittlement. ASA was developed for outdoor durability and is our first choice outside; PLA and ABS are poor choices for long-term sun exposure.

Outdoor parts face heat too: dark surfaces in direct sun get much hotter than the air. Combine UV resistance with enough heat resistance for your location — and remember that pigments matter, with black usually more UV-stable but hotter in the sun.

Some filament resins are made from food-contact-compliant grades, but that doesn't make a printed part food-safe. Layer lines and tiny gaps trap food and bacteria, pigments and additives may not be compliant, and the part passes through a hot nozzle and extruder that have handled other materials.

FORMYQ does not certify printed parts for food or drink contact. For things like cookie cutters or display props, tell us the intended use and we'll explain the options and their limits — sometimes the right answer is a printed mould or prototype for a part that is then made another way.

Most parts ship with supports removed. Sanding, priming and painting work on most rigid materials; flexible and fibre-filled materials are harder to finish. ABS is the only material we can vapour-smooth for a glossy, sealed surface, and only when it's listed as a finish on your quote.

Annealing — controlled reheating after printing — can raise the heat resistance of some materials dramatically (QIDI's data shows PAHT-CF going from about 85 °C as printed to about 191 °C annealed, both at 0.45 MPa). It also causes shrinkage and can warp parts, so we only anneal by agreement and allow for it in the design.

Each material has a relative cost tier from $ to $$$$. Price reflects more than filament: drying time, slower print speeds, nozzle wear, chamber heating and higher failure rates all add up for engineering materials.

Materials marked “In stock” use our standard turnaround. “On request” materials are bought for your job; we confirm availability, colour and lead time in your quote before you pay anything.

We only list materials that QIDI documents for these printers. That rules out very soft TPU (85A and below), which QIDI says should not be printed on its printers, and materials that need more than the printers' published limits: a 370 °C nozzle, 120 °C bed and 65 °C chamber.

If your part really needs something outside this list — very high-temperature polymers, resin detail, metal or machined tolerances — we'll say so honestly and point you to the right process rather than force a fit.