[@knowltonjayne]

Further user feedback

* If the top becomes unscrewed, the ¼”-20 nut can fall out easily. A small slip of paper folded a couple of times and wedged behind the nut will stop it falling out. Blue threadlock (the kind that’s reworkable with hand tools) may stop this unscrewing in the first place.

* If you’re short of ¼”-20 nuts (as might happen if one fell out and got lost, as above), you can 3d print a spacer from this OpenSCAD code:

in=25.4;
linear_extrude(height=7 * in/32)scale(2/sqrt(3))difference() {
circle(d=7 * in/16);
circle(d=in/4);
}

This has the width and height of a ¼”-20 nut, but should slip over the screw thread easily.