You can buy threaded inserts (see video below ... put nuts on the end and heat it up to let the nuts reform the plastic. This way the nut traps wind up the perfect size by definition.

Threaded inserts are great for melting into FDM prints ... while CA was comparable to plastic threads, failing at 52 kg. TLDR: Print your threads for best results [Stefan] also tested regular ...

The materials used for making threaded inserts are metals such as brass and copper, and plastics such as PVC and PTFE. A threaded plastic insert is more efficient than a threaded brass insert in the ...