This derivative of the Mendel frame vertex part has the option in the SCAD file of having a foot. The default file has one. I've oversized the holes slightly so that even people with wonky printers in development stand a chance of having a part they can use directly without having to ream the M8 holes out.

Using vertices with feet helps prevent the Z gears and drive hitting the table or objects that have rolled under the Mendel.

For a Mendel, print four of these with feet, and two without feet (you can use the original for footless ones if you don't run SCAD yourself). Arrange on the two triangular sides of the Mendel frame such that the feet point in a downwards direction and each triangle has one vertex without feet at the top. As a guide, if left to float free, components will generally accelerate towards the "down" direction.

If the surface you are placing your Mendel on is valuable and/or fragile, stick some felt, foam feet, draught excluder tape etc. on the underside of the feet. Doing so will also lessen transmitted vibrations and noise.

You can use vertices with feet on the top of the frame too, but it looks really stupid.