SHP countersink hole stop

# Background
While working on a charity: [Sleep In Heavenly Peace Syracuse NY](https://www.shpbeds.org/chapter/ny-syracuse) bed build event, I was assigned to the "clean-up" station, in which I was doing the finial touch-up of the head-boards. One of the operations, required countersinking the bolt-holes for the head-boards, required some finesse. The countersink tool is aggressive and I believe designed to work in a drill-press. It would "grab" and drill deeper than I intended... so I started thinking of solutions (**engineer always!** ).

I have settled on a single version (design 3) of this ... It requires a 6000 bearing for each depth stop. These can be sourced from wherever you buy bearings (or Amazon).
Design three uses industry standard "6000" bearings. Selected due to it internal bore is large-enough to print the 1/4" hex collar without being brittle, and due to it low cost (