This is a short list, but here it is:
RodneysRRTools.com offers several tools for the module owner. Among the various HO, N and Z scale tools are 3 N-trak tools and an HO step gauge tool.
The Switching & Sipping Society of N.C. have a template for drilling module ends, but does not sell the template. A standard, high-precision template is necessary for this type of module interface.
If you know of any other tools, please let us know by the comments form below or the contact form above.
I’m using the S&S waffle design on my new layout and have used it previously on two other small layouts. One of the 4×8 layouts I built using this system was so light that I could pick up the entire layout with scenery using only one finger. Photos on my website http://dixiecentralrailroad.blogspot.com/.