I use Freeman's square brass dowels for modules and lift outs.
These are the same dowels I used on Mike Reagons TAS traveling modules. They come in 10 different sizes for almost any application. Those European cam locks are slick but not too many folks are up to installing them.
Despite the naa sayers the brass dowels work well for passing track power. You can make wireless lift outs with them.
Coupled with a micro switch you can isolate track to protect open voids.
