I have found in the past that large leveling knobs are far better than small ones, so I created one that works for the HEVO. The nut is a VERY tight fit in the knob. This is by design. You can either pull out into place by screwing it from the top (before you put it in the printer and use a washer), or I used a longer m3 screw, put the nut part way on the screw, then hammered out in. The screw acts as a guide and keeps the nut level. Look at the pics for what I did.

I did my best to minimize the bridging at the top of the nut space, but you still may get a few stray strands. Just use a drill bit in your fingers to remove them.

On my HEVO, I used M3x50 screws for the bed. The knob takes an m3 nut.

I personally printed at 100% infill, but you can probably get away with less. Just make sure the shaft portion is solid.