I got the idea from https://www.thingiverse.com/thing:3726158. It didn't fit my jack pads so I made a similar design using OpenSCAD. PETG or ABS is recommended since the print needs to be heat resistant.

Jack Pads:
I purchased from Ebay at https://www.ebay.com/itm/273710639030

Printing:

Cutaway: Only for an example of internal detail.. Don't print this.

Top: You may want supports for the center but it'll probably be OK without them. I used selective 90% infill around the screw connection but 15% infill elsewhere.

Bottom: Supports not required. I used selective 90% infill around the nut pocket but 15% infill elsewhere. A 1/4-20 nut slides in the pocket to add threads.

Knob: Supports not required. Holds a 1/4-20 x 1" bolt for tool free attachment of top cover. I used selective 90% infill around the bolt head but 15% infill elsewhere.  See https://www.prusaprinters.org/prints/78501-14-bolt-knob for this knob's page!