This is a remix of the very good Universal Mount 525 for MPCNC. I just modified it so it can be attached to the MPCNC Primo Tool Mount by rsmitche as I use also a spindle and the universal mount seems a bit flimsy for that (full disclosure: I didn't try with it as I already had mounts for the spindle and rotary tool that fit the MPCNC Primo Tool Mount).
I attach this one when I want to use the pen, foam cutter, or whatever other small tool I have.