3d printing trick: when designing a complicated part that's supposed to interface with something (idk, a phone case):

1. Export a 2d drawing in 1:1 scale and print it on a regular printer. Cut it out and fit to the part. Pros: very quick and cheap iteration. Cons: meh precision, unless you have god-level scissors skills, hard time with non-flat parts.
2. Make a simplified template part that's quick to 3d print and fit that. If you got some dimensions wrong, adjust, cut away all elements that fit well and re-print. Pros: actually representative of the accuracy your printer will be able to give you, can fit non-flat parts. Cons: kind of slower, though not nearly as bad as printing and scrapping the full part.

Case in point: checking the rough dimensions of my phone and zoning in on camera lens positioning.