Now given that Sensepeeks sells spare isolation rings and sliding covers for a reasonable price (a roll of low friction teflon, ptfe or hmwd tape is not exactly cheap) -- we'll try to keep the design such that these are still usable should we want to.

And secondly - as we have some disk magnets  laying around - we'll want those to fit.

So that yield a quick design:

We have three parts; a Botton holder with an M8 thread and a bit of a hollow space for the magnet. 

A sliding thingy in the middle with a ID=8.5 OD=10, L=25 spring under it; and then a mushroom shaped thing at the top that is fixed into the Bottom holder. The spring size is not critical; these springs happend to be in the bits&bobs bin at the MSL.

Contrary to the PCBIte originals - we make the sliding thingy a little wider than the top mushroom bit. This is that, unlike the original where you have a fair bit of grab-space thanks to the hight, so you have something to help you push down on.

And as we really like knurling - we'll need to find a reason to that.