<p>I’m designing a part that will need to be autoclaved—it will be under steam at 121°C for about 15 min per job and I will want it to be able to go through the autoclave repeatedly. I ran a test PLA part through the autoclave and it warped noticeably; based on their glass transition temperatures, ABS (105ºC) and PETG (80ºC) would probably also not hold up. For a consumer-grade FDM printer, what filament materials that could be used for parts that could be autoclaved?</p>

It might seem that common 3D printer materials such as PLA and ABS should be capable of being autoclaved—unfortunately. However, although their melting temperatures are higher than autoclave temperature (typically 121ºC), their glass transition temperatures are below that limit so they can warp or undergo creep deformation.
Sterilization of numerous plastics is described
here
, with PLA, ABS, and PET all being described as "poor" for autoclaving. For each "good" material on that list, I looked for filament by Googling and consulting material guides from
Prusa
and
Matter Hackers
.
Polypropylene (PP) or acetal (POM, also known as Delrin) are the best choices. Filament is available for PEEK, PEI (ULTEM), FEP, PPSU, and PPS but these filaments are expensive (>$100/kg) and require high extruder temperatures (>300ºC).
In contrast, PP is about $50/kg and uses an extruder temperature of 254ºC; POM is similarly priced and uses an extruder temperature of 210ºC. Nylon (depending on the exact type) and HT-PLA may also be worth considering.
"High temperature" filaments are not worthwhile for this application. Again, they're expensive and, more significantly, do not work well with consumer-grade 3D printers. For example, the upper limit for a Prusa i3 MK3s is about 280ºC—the thermistor only is good up to that temperature. Higher temperatures would require swapping out sensors and modifying firmware and building an enclosure.
It's been done
. Printers designed for high-temperature filaments easily cost
thousands of dollars
.
This question was previously asked on
Reddit
a few times
but this analysis is more comprehensive.