Those small composition magnets used in door catches can be removed and trimmed into smaller pieces (to reduce to force needed for removal of possibility delicate structures - you don't need a lot of force to keep them in place, gravity is on your side, and I assume you''' rempve and stre them before folding up the layout) that align with small steel plates (magnets in "foundation" on layout - easier to clean up stray ferrous bits that might be wander by and become atracted, plates recessed into base of structure). Electrical connections for lighting or animation motors can be made less subject to critical alignment fiddling by using pads of springy sheet brass or phosphor bronze or such - easily cleaned with an alcohol rag. Made large enough, say 1/2" square, the alignment is not that tricky.