Like any good builder, it helps to have a plan before construction. I based the design of my Mek Shop on the one from the Dawn of War game. The half-pipe shape is reminiscent of the quonset huts used by the U.S. Military for years and has a very utilitarian feel to it.
 
The first step was to grab a couple of screen captures from Dawn of War to give me something to start from.

Another screenshot from a different angle.

I love the scrapped Leman Russ chassis laying on it's side. Lucky me, I just happen to have an extra Russ layin' around.

A couple of mockup shots for scale purposes.

The interior dimensions of the shop will hold my Looted Russ with room to spare.

I made the building mockup first so I can get an idea of the size before I go and start cutting the MDF for the base. Cardboard is a hell of a lot cheaper than MDF board.

I'm liking the look of things so far. Rivets, gubbins, and a whole ton of bitz will make a lot of difference.

I picked up this toy crane in a generic 'construction playset' I got at the supermarket. You know the kind, they're the 'el cheapo' toy sets you see on the very top of the shelf when you're wandering around looking for groceries.

I'm not sold on the idea yet, but I'll definitely make the base for this big enough to accomodate it, should I change my mind.

As you can see here, I 've added a base to the Mek Shop. I've also filled in the edges of the cardboard with plaster fill (the kind of stuff you use to repair holes in sheetrock).

I've also made the roof removable.

Here's a shot with the roof removed

View from the front.

And again with the roof off.

I added a small lean-to shed to the back of the Mek Shop.

The roof for this addition is made from corrugated cardboard (like the rest of the shop) with the outer layer removed, and is also removable.

A view from the other side.

After the glue dries, I'll sand down the excess plaster fill. Then it's time for gubbinz...