Match material to exposure
PETG is useful for straightforward indoor aids and clear iteration, while ASA can suit covers or guides that see warmer ambient conditions and more ultraviolet exposure. TPU adds compliant contact, grip or masking, but it can creep under sustained load. Carbon-filled PETG or PA can increase stiffness and dimensional stability, yet printed layer orientation and geometry still govern performance. The material name alone is never a load rating.
Plan wear interfaces
Pins, drill bushings, threaded inserts and replaceable pads move concentrated wear away from the printed body. A good design makes these elements inspectable and serviceable. Abrasive parts, chips and repeated clamping can change a locating surface over time, so define an inspection interval and a rejection condition. If a worn surface would create an unsafe process, use a qualified metal solution or independent engineered control.
Declare heat and chemicals
Share operating temperature, cleaning chemicals, oils, coolants, adhesives and any welding proximity before quotation. Short contact and continuous exposure are different conditions. Printed polymers can soften, swell, become brittle or burn, and carbon-filled materials may be electrically conductive. Trial the approved material in the real environment, maintain guarding and extraction, and do not use a polymer fixture as pressure containment or life-safety equipment.