We live and game in a four car garage; with all this space available, everything tends to walk.  The ill-used third table is a nexus for all things orphaned, and on any given day it overflows with gundams, lone aegis defense line sections, regret.  Our models were everywhere, and a long-ago visit to a friend's smaller gaming area had shown us the light: display cases.  While we weren't up to cutting glass and making hinged doors, we roughed out a idea for a place where all our models could live and work.


We wanted this to match our custom gaming table, so the height was based on that height.  It has to fit alongside some permanent fixtures, so it's width was limited.  We were shooting for a five foot tall, six foot wide, 18 inch deep shelf structure.  I did most of the cuts and screws, but my friend Ezra bankrolled the thing, so he gets all the credit.
I (mostly) won't be giving exact measurements, because I didn't write them down.  If this inspires you, you'll have to make it fit for your personal space, and please, try to do it better.  We were just ok.

Total time: ~5 hours.  Total cost: ~$60
Needed Materials:
2 sheets of 1/2" plywood
4 ten-foot sections of board
Wood Screws
Table Saw
Drill
2-3 yards of premium felt (get a coupon for 50% off at joanns, sukkah!)

We started off by cutting the 2x4 boards into two 54" sections, four 18" sections, and two 24" sections.  This consumes two ten-foot sections of board with just a little waste.  Then screw them together...with screws.  This makes our "tertroids."
 
Damn, missed a couple steps of camera.  So we cut out some plywood to make the top and bottom shelves.  Here is where we made a critical error - the space between the diagonal joists should be six feet, the width of a piece of felt.  Instead, it's six feet minus the width of two joists.  This made a headache later when we covered it.  There is a plywood shelf underneath as well, that lays over the bottom of the two boxes we made in step one.  To make the joists, we laid the board to be cut underneath the tetroid and marked the angles, then cut with the table saw and an angle attachment.  Geometry is hard, kids!
The next step was to attach a plywood sheet between the joists that sits flush with the middle shelf.  This provides the backing for the shelves and some structural integrity.
 



To attach the shelves, we cut some small pieces and attached them to the joists, and cut six foot strips that run across the plywood.  Then another strip (~1/2"x1") runs across attached on the outside.  The top shelf is 8" down from the top, the second shelf 10" down from that.  I did a terrible job on the shelves, with additional supports that stick out, but they got covered later.  Again we made a mistake here, the top shelf need to be at least 10" deep  to accommodate flyers.  As it is, it fits the base but not the aircraft itself.  The top shelf is 8" down from the top; if you want a narrow shelf I would place it 3-4" inches from the top so the vehicle hull will clear the structure.  This would make the two middle shelves easier to use as well.  As it is, the fliers only fit on the bottom shelf!  However, we're confident they won't fall down and break there. 

Another shot of the attached supports.  I added rails on the very bottom on the inside of the tetroids to add stability.  I also added a strip where the plywood sheets join, which looks ugly but was easy!
 
 
Ready for transport.  The shelves are sheets of plywood.  You want to screw them down pretty good because plywood tends to bend over time. At this point, we realized we should have made the whole thing six feet tall, to give the shelves some more room to breathe.  Having some models available would have been a really good idea for a sense of scale.  At least ten inches between each shelf would be ideal. 
 I cut some nicer boards out that will be the bumpers.  They should run all the way between the joists for the two shelves, and the full width of the display for the middle.  These are to cover up the pine boards and make a small lip so minis won't walk out on us.
To attach the felt, we started under the middle shelf and just went crazy with the staple gun.  You need short staples and a powerful gun to pierce the wood.  Tack it down at every corner and pull the felt to make it tight.We have some staples sticking out, but we pretend not to notice them.  The felt does wonders in covering up mistakes and bad angles.  We bought three yards of felt, two would have been fine, but the extra hangs down all the way in the back.  It would work to flip over and dust-proof the shelf if we were ever going to stop playing regularly.
After the felt is attached, the bumpers go on.  These are about 2", so they further stabilize the shelves and cover up the uglier parts of the felt attaching.  This is much easier than sanding/staining/finishing the whole thing.  I used two six foot boards of nicer wood to make these bumpers.  Now the only pine exposed is the legs, and you won't notice them with all the amazing minis up top!
Couldn't get a picture assembled before everyone gang-rushed the thing and staked out some territory.  The bottom section's dimensions were defined by our many identical plano cases.  We can fit three and the two odd-size case perfectly.  Now every resident army's travel case fits in the display.
This entire project was what I call "emergent carpentry."  I came in with a rough idea and just went with it.  I didn't plan my cuts for the entire project, I just made things that fit and figured it out as I went along.  Much like modeling, it can be better to let your materials communicate and to find your own skill level.  This could be much nicer, of course, but that would have tripled the time investment.  We got it done, it looks great, and everybody can make fun of me for the little inconsistencies in the creation of the thing. 
This is an incredible space saver, because most of these models were spread out everywhere, getting in the way, not looking awesome.  Having everything centralized and deployable directly onto the main table two feet away is going to make a big difference in our play.