Ok, you guys have been really helpful thus far. Here's what I need to know now. I'll use a hypothetical situation. I have four double boxes. I'm going to make a wall that looks like this (each [] is a box) [][] [][] I have no trouble merging the boxes together cleanly as long as they are on the same level, but how do I merge the top row with the bottom row cleanly? How do I make sure the top of the wall is even? Mine always winds up like this. (the - is the top of the second box in the top row) []- [][] I'm stumped and cant figure out how to keep them at the exact same height. Any assistance would be greatly appreciated.
Flip a double box on it's side. Then place the one you're interlocking for the wall on top of the flipped one. Make sure you line them up with walls or whatever you use to line things up so they're nice and clean.
or you could put a wall ontop of the lower boxes, then make the boxes not appear at start, then start a new round, place a wall exactly underneath the other walls, then save and quit, then repeat process so that you have 3 walls floating in the air, then delete the top two, so you only have the lowest one floating, then put the boxes ontop of that, and delete the wall, and then wait for the box to spawn, it should be a perfect interlock if you did it neatly.