O'Reilly logo
  • Dave Nelson thinks this is interesting:

The best way to fit nuts and bolts (the hex heads) into plastic parts prior to assembly is to heat the nut or bolt with a butane torch, and then insert the heated metal into the part. This is really great if the opening is just a tad too small, as it will make a very tight setting for the nut or bolt.

From

Cover of Maintaining and Troubleshooting Your 3D Printer

Note

Use heat to set metal parts into PLA