The material choice for an FDM print shapes every meaningful characteristic of the finished part: stiffness, impact resistance, heat tolerance, UV stability, and how easily the part can be printed in the first place. Most desktop 3D printing uses one of a small number of thermoplastic families, each with distinct handling requirements and performance ceilings.
Understanding the differences between these materials before starting a print — rather than discovering them after a failed build plate adhesion or a warped part — is one of the more practical pieces of knowledge for anyone working with a desktop FDM printer.
PLA — Polylactic Acid
PLA is derived from fermented plant starch (typically corn or sugarcane) and is the dominant material for desktop FDM printing by volume. Its appeal is almost entirely practical: it prints at relatively low temperatures, adheres well to most build surfaces without a heated enclosure, and produces minimal fumes during printing. For parts that don't need to tolerate elevated temperatures or mechanical stress, PLA covers most use cases.
The principal limitation of PLA is its glass transition temperature, which falls between 55–60°C. Parts left in a hot car interior during Canadian summer can deform. PLA is also more brittle than PETG or ABS; it fractures rather than deforming under impact. For functional mechanical parts that see impact or elevated heat, a different material is typically selected.
PLA+ formulations sold by various manufacturers include additives that increase toughness and impact resistance while maintaining similar print temperature requirements. These are not a standardized specification — the actual properties vary between brands.
PETG — Polyethylene Terephthalate Glycol-modified
PETG threads a line between PLA's printability and ABS's mechanical performance. It has higher impact resistance than PLA, a heat deflection temperature around 80°C, and good layer adhesion that results in parts with useful strength in the Z axis. The glycol modification compared to standard PET reduces crystallinity, making it less prone to warping during printing.
PETG does string slightly during travel moves — thin wisps of material that form between features — more than PLA does. This is manageable through retraction tuning in slicer settings. It also bonds strongly to PEI surfaces when hot; waiting for the bed to cool before attempting to remove prints prevents delaminating the PEI coating.
In Canada, PETG is commonly used for outdoor brackets, tool holders, and functional enclosure parts where PLA's heat resistance would be insufficient but the cost and complexity of ABS printing isn't warranted.
ABS — Acrylonitrile Butadiene Styrene
ABS was the material of choice for early desktop FDM printers before PLA became dominant, primarily because early machines were based on industrial FDM machines where ABS was standard. For home use, ABS has largely been supplanted by ASA for outdoor applications and by PETG for general functional parts, but it remains relevant where acetone smoothing or solvent bonding is part of the workflow.
ABS warps significantly on open-frame printers. Successful ABS printing on a desktop machine generally requires an enclosed build chamber to maintain ambient temperature above 40°C. Styrene vapors released during printing are an irritant; enclosed chambers vented through an activated carbon filter address this.
ASA — Acrylonitrile Styrene Acrylate
ASA was developed as a UV-stabilized alternative to ABS. The acrylate component in its polymer chain provides resistance to UV degradation that ABS lacks. For outdoor signage, automotive trim prototypes, and fixtures exposed to sunlight, ASA maintains its mechanical properties and color stability significantly better than ABS or PLA over time.
TPU — Thermoplastic Polyurethane
TPU is a flexible filament family with Shore hardness ratings typically between 87A and 95A for consumer materials (lower Shore A = more flexible). It prints at moderate temperatures but requires a direct-drive extruder for reliable feeding — the filament compresses in a Bowden tube rather than pushing through cleanly.
Engineering Materials
Nylon (PA)
Nylon offers high toughness, good fatigue resistance, and low friction — properties that make it useful for gears, bushings, and snap-fit joints. It is highly hygroscopic: even brief exposure to ambient air causes moisture absorption that manifests as bubbling and weak layers during printing. Nylon filament must be stored in a dry box and printed immediately after drying at 70–80°C for several hours. Printing nylon reliably requires an all-metal hotend and a heated enclosure.
Carbon Fiber Composites (PA-CF, PLA-CF, PETG-CF)
Carbon fiber composite filaments are a base polymer (PA, PLA, PETG, or ABS) filled with short carbon fiber strands. They are significantly stiffer than unfilled variants — sometimes dramatically so — and lighter. The carbon fiber is abrasive: standard brass nozzles wear quickly, and hardened steel or ruby-tipped nozzles are required for sustained printing. These materials are used where rigidity-to-weight ratio is important: drone frames, lightweight brackets, jigs and fixtures.
Moisture and Storage
Most FDM filaments absorb moisture from ambient air over time, with nylon, TPU, and PVA being most sensitive and PLA being moderately so. Moisture-absorbed filament produces audible crackling during printing and creates voids and surface bubbles in finished parts. Dry boxes — sealed containers with silica gel desiccant — maintain filament at low humidity for extended storage. Several consumer-grade filament dryers with temperature control are available specifically for this purpose.
Canadian climate note: Winter indoor heating in Canada reduces relative humidity substantially — often below 20% RH — which can benefit filament storage compared to more humid climates. Summer humidity, particularly in coastal and Great Lakes regions, warrants more careful storage practices.