Quick and dirty approach for a template to mill round corners with a hand-held milling machine.

!!! CAUTION !!! Only use if you know how !!! Use on own risk !!!

First picture: Be aware to cut of most of the material before milling !!!
Second picture: Fasten everything very careful to the workbench before you start.
Third picture: :-)

Pint-Settings:

Supports: None
Infill: 10-20%
Material: PLA is enough