How do I print structural things (cup holder, pin, etc.) for the inside or outside of a car?

• standard PLA is out: heat sensitive
• there's ePLA and PLA+ and other special PLA that claims to be more heat sensitive. Reviews are sketch and brands unrecognized
• ABS would require printer modifications
• PETG might be a reasonable compromise?
• PETG on Ender 3

Whatever material used, it seems the annealing process will be important

• method for annealing: tl;dr use sand and a toaster oven
• annealing experiments: tl;dr 110*C for PETG