Mike, the alignment pegs are scaled down from something similar to the GW models pieces seen in the front of MRJ each issue. I set them up to use hardware I have around for cabinet making - they take a number 5 robertson. Concern I have at the moment is that the modules might not go back together if the individual modules are stored in areas with differing humidity, there being only a few thou of play in the pegs themselves. Going with a single set of alignment pegs might aleviate this problem but so far I've set my modules up to work with two. We (my friend doing P87 Ozzie broadgauge and I ) discussed using a modutrack like leg with this system but the clamping part of the leg would need to be very flexible to allow both modules to fit on AND the gap required of the male alignment peg. I suppose the protrusion could be reduced but I don't know by how much. I ended up going with normal legs set up in pairs. When I made the pegs I did so on a Taig lathe and I was just glad to have them done to my original specs. I now have a much larger lathe and can machine them much quicker so some experimentation might be in order.
Andrew Hutchinson
What I'm considering with our system, given the problem you realized above with protrusions on the ends of modules that need to slide together, is to put a threaded insert in one module, through hole in the next, and just use a threaded knob to then clamp the modules together. A little play in the through hole will allow for alignment, and that bit of clamping force with the threaded knob should keep things from moving around when the layout gets bumped. The HO Modutrak guys have done a similar conversion and report good results.
If the modules don't need to slide together over a shared leg, then I also like hinges at the joints. They align positively three dimensions.