It's a spindle for your grinding discs, what more do you want?

The top features a chamfered edge to make it easy to put the discs on and I've added a through-hole and some slots for added strength and lower material cost.
There's also a little cutout on the bottom to pick up the last disc more easily.

Total diameter is just under 140mm, height is 70mm so you could extend it or make a gridfinity variant of this if you want.

I've printed this using PETG with 5 top/bottom/walls and 30% gyroid infill and it took about 50 grams of filament, I wanted the spindle to be durable, but you're free to tweak this to your liking.

There's a second (untested) variant with a screwhole mount which should work if you want to hang it from a wall instead.