I doubt that this is the first time someone has mentioned this but I ran a little experiment over the weekend. I printed out a phone case and it turned out great. When I tried to put it on the phone, it snapped on just like I wanted it to, but the last corner was just a bit too tight.
I thought – What can I do to make it just soft enough to snap into place?
This was a PLA print (I would not recommend this or ABS or any other more toxic material).
I turned on the oven and cranked it up to 300 degrees. Once I had it warmed up, I placed the phone case on a piece of paper towel on a cookie sheet – parchment paper probably would have been a better choice but neither will burn at that temperature. Once the phone case had been in the oven for just a little while, it became very malleable. I stuck the phone in the case and then placed it on a marble countertop, so it cooled down very quickly.
With only a minor distortion of the case, it worked, so I thought I share the experience, since I didn’t need to throw the case away to make a new one that was only half a millimeter longer