A vacuum mount with exchangeable adapters for my CNC (CNC3020) router.
An upgraded version with pen and auxiliary holder can be found at:
I have kept this version as some might prefer the simpler design (or doesn't need the extra feature).
The mount should be scaled for shrinking (1% for ABS). The adapters should be left as they are. This way they will fit perfectly. I recommend printing the adapters with 0.15mm layer height because of their sharp angles.