I'd like to start a discussion of 3D printed parts used to replace/upgrade parts on cars, as well as what you've learned about using various materials in certains applications.
I'll start. Most of my filament is re-branded esun stuff.
PLA: I have no use for this directly. It's by far the most common and easiest to print. It's low glass transition temperature and melt temperature make it not very good for most functional applications under the hood. It does have one advantage, you can use it to make molds for aluminum and brass castings, but it does leave ash behind without post-processing. Needs a material fan "blowing" at the nozzle for small parts/overhangs.
Wax: Useful for making ash-free casting molds. But much more difficult to print than PLA. Nearly impossible with a 1.75mm hot end, which by design has a max OD of 1.8mm, where the 1.75mm nominal wax seems to vary from 1.68 to 1.83mm (I've only ever measured or tried one roll). Absolutely need to fine tune the bed and nozzle temperatures, must use a material fan "blowing" at the nozzle.
ABS: Learn to love it, build an enclosure, whatever it takes. Get the first layer to stick, and you're golden. It had great resistance to under-hood heat, doesn't appear to warp. I've been monitoring a test "clip" on my '97 Camaro for 8+ weeks now, it's clipped to the heater hose right above the header, no warp, hasn't fallen off in spite of *shoot* SE MI roads, etc. I had to resort to ABS juice to make it stick to the bed on my printer. One part, in fact, a 6" x 6" piece, ended up shattering the glass bed when it tried to warp, pulling up on the 10x10 glass that was secured at the corners. I've got a material fan "pulling' air from the nozzle, seems like it's just enough to cool off the ABS for overhangs without screwing up the layer adhesion.
PETg: Easy to love, prints like PLA with a material fan, similar physical characteristics as ABS, very good visual characteristics. Sounds like a dream recipie. However... NOT suitable for use in an engine bay. Parts will deform, fall off, etc. Appear to be very susceptible to residual stresses and/or creep below the glass transition temperature.
My biggest issue is engine bay reliability. My experience has been that ABS is the absolute minimum for use there with 3D printing. Other candidates may include PC-ABS, PC, Delron, nylon, and nGEN. But the trade-off seems to be warp during printing (causing failed prints). PETg seems to work for non-UV applications that will not achieve normal underhood temps.
That being said, what kinds of things have you done with 3D printing automotive parts? My prints have been mostly hose organizers and replacing broken 40 year old plastics:
