A double peg for stubborn pieces that won't stay put.
This post and perhaps the scad script need a lot of refining but I wanted to put it out there to anyone attempting the project. These pieces are perfect for the 90 degree VMR and the stubborn straight tracks or anything else that won't stay put.
Search VMR or vertical marble run for more details...
Original thing write up:
I will update when I have a chance - there are more pieces and custom student pieces to document.