I have an idea for a simple and inexpensive set of modules that could be assembled together to make one layout or added to a collection of modules (club?) to build a bigger layout. The multi-purpose and portability of the concept is very appealing to me for several reasons. I don't have a whole lot of space to play trains in right now; I'm planning on moving fairly soon (couple years); and I'd like to be a member of a club and we happen to have an active modular group in the area. So having not gotten any information from the local club about their module specifications I started out examining my options (cart leading horse, standard procedure). I assume they use the nearly universal 2' x 4' module size with 5" and 7" mainline centers and I hope they use HO. Otherwise this will get really expensive for me, and that's something I'm attempting to avoid. Without further ado, my concept is to use four 2' x 8' tables with modular standards for mainline ends that also have curves for connecting the four tables together in a square, 10' x 10' with a 6' x 6' operating 'hole' in the center. Using XTrkCAD I've tried lots of techniques to make the turns, and come up with some interesting ideas. Working with a 20" radius I made a few attempts to get around the bend. The top left corner is by far the simplest route, but creates a curve at the module joint. Is this bad? In the bottom left I was able to connect to the end of an existing main line and only used one turnout, but generated two curved crossings - in other words, highly unlikely. In the bottom right I made maximum space on the right side module for a possible small switching yard. I also avoided a curve on the joint, but it is forced to have another set of curved crossings. I would imagine that the club module standards call for a 1 or 2 inch inset on the rail for a joining piece. That's not a problem. But is it ok in private use to have curves over the edge of the modules, and no joining piece? Is this a viable concept? What recommendations do you all have?