Tons of things can be 3D Printed. That is my day job.

Some of things I've done:
-TPS sensor adapter plate to put a DSM TPS on a Mustang throttle body
-Adapter plate for the little coin holder in a 1G to mount a power outlet
-Cam gear tool to hold gears in place when doing the belt
-Degree wheel tool for DSM
-Wire loom tool. Makes it easy to put wires into the split convoluted tubing.
-Custom gauge mount for dash
-Seal driver adapter
-Intake piping (size) adapter
-pulley aligning tools (serpentine belt)
-'69 Chev heater box repair (air door)
-shifter bushings

A bunch more.