I wanted to mount a filament spool above my mendel, so i made this thing.

It clamps onto the two top frame rails, between the Z axis guide rail and the frame. The top of the Z axis drive screw goes through the hole in the middle of this thing.

Print one of each part, or two of part A.
Bolt them onto your mendel and you will have two 8mm holes for vertical shafts.

Part A includes a cutout so that it can be fitted around the Z axis drive screw.

Use M4 screws to clamp this thing. Fit two screws to each side.
Install 8mm threaded rod to support whatever you want to support. In my case it was a filament spool.