This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/9OE2dVcuOiN

with two of these adapters, you can easily replace the body of your reely R/C car with your own lego technic body.

The part is designed in such a way that it is easy to print.
No special settings needed if you lay it flat on your printer bed.