Holder for a hole saw with switchable blades. Base is a 2x4 gridfinity grid. Fits:
The adapter (70mm)
The drill bit (8mm x 100mm)
6 Blades sizes: 25/26 - 32 - 40 - 45 - 54 - 65/66 (size different per manufacturer but both fit).
For bigger saws see:
https://www.printables.com/model/1089451-gridfinity-big-hole-saw-holder
The author remixed this model.
Complete redesign with deeper groves, more fitting to the standard hole sizes and fits the drill bit.