Inspired by the great Gridfinity Dremel 8260 holder by @sacrilegor, this holder fits the Dremel 8220 and has optional holders for chuck collars, the chuck wrench and the Dremel 636 wood drill bits.

As seen in the pictures, the holder itself needs a grid size of 2×6, but the font of the Dremel sticks out a bit and in my case (with a 4486 variable Chuck) almost needs a whole additional block. You could probably fit a bin with a height of 2 or 3 under it, tough.
So I recommend planning with a size of 2×7 for this holder.

Compared to the pictures of my Print, I improved the tolerances for the drill bits and chuck collars and flipped the way the chuck wrench is oriented by 180°, since the wrench was a bit close to the Dremel itself.
(Haven't printed the improved iteration, since my first try worked just fine after drilling out the holes)

Be aware, while the front part of the holder fits snugly around the Dremel, the backside is a bit loose.
However, the Dremel doesn't move around, even when I'm opening the drawer it sits in with a bit more force, so the fit shouldn't be a problem.