I admit I've backed off from experimenting with modular builds for a while now. I've released a handful of static buildings that are exterior only, and I just released a ruined building set that has interior textures out of necessity. It's even a little bit modular and kinda lets you fold flat the structures.
But, I still want modular builds!
My latest plan seems to have enough merit for me to try for real on a couple tiles. What I've done is carved parallel slits in the corner of the tile that will be affixed to foamcore. Then, I've got little tabs that can slip under the tile face through the slits and fold upward, giving the posts something to grab onto. You only need to slip in the tabs that you are using, and they aren't glued in place. The tabs aren't even textured, so there's no laborious edging to do.
Time is always my enemy. Tonight, I've got a cub scout overnight camp to live through, and who knows what has been planned for me this weekend. My hope is that I will be able to take one of my released sets and make a set of 3" or 6" tiles, some posts and walls, and see if everything really goes together nicely. I also need to prove to myself that I can hand-cut these things AND that it doesn't look like poo when I'm done.
The scraps that I cobbled together work pretty well, though, so optimism continues to reign supreme.