PLA is the correct starting filament for the vast majority of hobbyist prints. It prints at the lowest temperatures of any standard filament, barely warps without a heated enclosure, produces excellent surface finish and fine detail, and is available in the widest range of colours. It is also bio-based and biodegradable under industrial composting conditions.

The limitations are real but predictable. PLA softens at approximately 60°C — below the temperature of a car interior in summer, below the temperature of direct sunlight on a dark-coloured surface, and below the temperature near some light fittings. It is also more brittle than PETG or ABS under sudden impact loading.

Display models, figurines, miniatures, desktop organisers, indoor wall mounts, prototypes for visual review, educational models, decorative prints, and anything not subject to heat or significant mechanical stress.

PETG is chemically related to the plastic used in water bottles — and it shares the same toughness and impact resistance. A PETG print that takes the same knock that would crack a PLA print typically flexes and recovers. PETG is also food-safe when printed correctly with a food-safe nozzle, making it suitable for containers, kitchen tools, and water-contact applications where PLA is not.

The trade-off is that PETG strings more during printing than PLA — thin strands of filament appear between separate parts of the print during travel moves. Managing retraction settings in the slicer addresses most of this, but PETG takes more tuning than PLA to print cleanly. It also adheres to the build plate very firmly, which can make removal of prints harder.

Mechanical brackets, clips, enclosure panels, functional replacement parts, food-contact items, anything requiring impact resistance PLA can't provide, and parts used in mildly warm environments up to approximately 80°C.

ABS is one of the most widely used engineering plastics in manufacturing — it's what LEGO bricks are made from and what most vehicle interior trim is produced in. Its heat resistance (up to approximately 100°C) makes it suitable for parts near heat sources, in engine bays, or in enclosed hot environments where PETG and PLA both fail.

The requirement is an enclosed printer. ABS shrinks significantly as it cools, and without a consistent warm ambient environment maintained by an enclosure, prints warp and delaminate. On an open-frame printer like the base Neptune 4 without aftermarket enclosure modifications, ABS is difficult to print reliably. The Neptune 4 Max's larger build volume can accommodate an enclosure tent if this use case is important to you.

Automotive interior parts, electronics housings near heat sources, any indoor functional part requiring heat resistance above 80°C. Use ASA instead of ABS for any outdoor application.

ASA was developed specifically to solve ABS's outdoor limitation. It matches ABS's heat resistance and mechanical strength but adds UV stabilisation — meaning it does not yellow, fade, or become brittle in prolonged sunlight. For South Africa's high-UV environment, ASA is the correct outdoor filament. An ABS print left outside will degrade visibly within months. An ASA equivalent will not.

Like ABS, ASA requires an enclosed print environment and a high bed temperature. Print settings are similar to ABS but temperatures run slightly higher. The surface finish is marginally more matte than ABS, which in most outdoor applications is a non-issue.

Outdoor signage, garden fixtures, vehicle exterior brackets, cable management clips exposed to sun, irrigation fittings, and any print that will live outside in South African conditions.

TPU is a flexible, rubber-like filament that opens up a category of prints impossible with rigid materials. Phone cases, vibration-dampening pads, flexible seals, cable organisers that grip rather than slide, and wearable bands all require the flexibility that PLA, PETG, and ABS cannot provide.

TPU requires slower print speeds — typically 20–40mm/s on direct drive extruders — because the flexible nature of the filament makes it prone to buckling inside the extruder at higher speeds. The Neptune 4 series' direct drive extruder handles TPU well at appropriate speeds; Bowden-style extruders (where the extruder motor is mounted remotely from the hot end) struggle significantly with TPU.

Phone and tablet cases, vibration dampeners, gaskets and seals, flexible hinges, cable organisers, shoe insoles, wearable straps, and any part that needs to bend without breaking.