[ConnalM]

The system I have adopted is to use the R1 radius as the entry exit spacing. It works fine for me, as I can connect pretty much any module to any other module; and I am quite happy to adopt that system for a routed track system. Similarly, I am happy to adopt the rest of the Scalextric dimensions, as this gives me a simple segue from the modules I have.

Not sure what you meant by 'border material'.

I can see the advantages of having the modules the same dimensions (as mine are currently) but I can see that there is a big saving in having them just a little bit bigger then the routed track itself.