D-Bot bed leveling with big knob, 2020 version

Modified the knob to allow for a deeper recess for the nut, to use an M3 Nyloc nut.
Also shortened the base, to allow for it to be mounted on a 2020 extrusion.

Can be mounted upright as the original part, or upside down so the adjustment wheel is underneath the extrusion.

Recreated the part in OpenSCAD, in case anyone needs to modify it.