Not sure what to print it in? That's my job.
The wrong filament is the most common reason a part fails. It totally depends on the application: heat, load, sunlight, chemicals, how much it has to flex. Tell me where the part goes and we'll pick it together.
High temp PLA with glass fiber, the Polymaker stuff. Most of what leaves here is printed in this. Mid grade strength, holds up to heat, prints clean. If you don't tell me otherwise, it's probably what I reach for.
Cheap, accurate, stiff. Fine for models and shelf parts. Leave it on a dash in July and it'll sag on you.
Tougher than PLA and it shrugs off most shop chemicals. Good for parts that get handled every day.
PET with glass fiber. This is what finally solved a cracked fixture I'd already tried in polycarbonate. Stiff, and it doesn't creep on you.
Takes a hit and takes heat. Enclosures and pieces that live under a hood.
Stays put in sunlight. If the part lives outside, this is the answer and I won't talk you out of it.
Gaskets, grips, bumpers, anything that has to squish and come back.
Wears slow. Gears, hinges, bushings, things that get worked.
Impact and heat at the same time. Worth knowing it's flexible, which is sometimes exactly what you want and sometimes the reason a part keeps moving.
Carbon fiber in the nylon. Stiff, stable, holds its dimensions.
Low moisture pickup and good chemical resistance. For parts that get wet, oily, or greasy.
Fair warning, ask me about filament and I'll talk longer than you wanted. If something you need isn't on this list, I can usually source it.