This is a replacement for the blade holder model the MMU2 shipped with. The blade kept coming out of the original model.
any PLA, ABS & PETG
The mounting bolt holes were reduced to 0.15 mm clearance.
The pin holes are 1 mm, sized for 0.025 inch square pins on 0.1 inch spacing - common PCB pin header pins.
Leaving the pins in the PCB header housing until they are inserted will make sure the flat of the pins is flat against the flats of the blade. I also left the housing in place until after I pounded in the pins, which obstructed one mounting bolt during assembly. I just aligned it with one bolt and ensured it was rotated right visually before setting the pins, then installed the second bolt after clipping the pins.
Remove the tube fitting, it's on the surface the mmu2-selector-finda will lay against when the pins are pounded in. I also removed the PINDA probe to avoid damaging it, after marking it's position with a felt tip marker.
Push some pins through the holes until they protrude slightly through the other side.
Install the blade and bolt it to the mmu2-selector-finda with the unobstructed bolt and position it correctly.
Pound the pins into the mmu2-selector-finda a couple millimeters. Some pins will run into mounting nuts if inserted too far and a few millimeters is more than enough insertion.
Clip off the exposed portion of the pins and pound them in enough that they are fully inserted, I used a small punch for this.