O.k. I'll admit it, the topic line was a streach to sensationalize my problem and get you to look.
I'm building my first project (it fits and bursts, it seems) which is a firstlight spaceship for a Star Wars game. I have the rooms for the lower level built, and am ready to mount them, but my floor plan it too big to fit on one peice of foamcore. I'm going to have to chunk it up into sections, which isn't really a problem.
The question is, does anyone have any tips for lining up my mounted sections so they "Mate" nice and smoothly?
I was figuring I would just put them all down and put tape on the underside or something, but you all have much more experiene at these things, so I thought I would toss the question out there and see what came up.
Thanks!!

PS-- I know I didn't need to trick youwith talk of mating. Everyone has been super helpful on these boards, so I want to say thanks. I'll put pics up of my work in progress as soon as it gets to a more progressive state.

That was a better title than "Mounting your Mates"

Try maybe getting those thin magnetic sheets that have sticky on one side. have an "overrhang" underneath one section, with the other section having a corresponding magnetic strip (make sure their "polarized" or you end up with a "force field" that prevents mating. The sheet can be bought in like 8"x8", or in thinner strips, and is easily cut with scissors.

It looks like Andorax has managed to decipher my question.
Splicing the two sheets of fomecore together may be the best way to go for me.
I thought about keeping the sections seperate (engenieering, crew quarters, astrogation, etc.) and finding a way to nub them together when I need them, but this is my first ship design, and I didn't really do a good job of plotting it out so that would be a viable option. (the large, non-removable cargo area in the middle of the ship is the spoil sport there.)

Thanks to everyone again for your help on this. The best part about taking the plunge into doing paper terrian is knowing there's lots of freindly folks with good advice!