Was at my local resale shop when I found a little plastic building in the random-toy-crap bin. It appeared to be part of some micro machines toy, but seemed like just the thing for my 10mm rebased mechwarrior vehicles.
Here's how it arrived
Disassembled with stickers removed.
I had ordered some GZG 25mm doors, vents and windows so I cut them down to make doors out of windows, thin windows out of big ones and ovehead door out of a vent. Similar effects could be achieved more cheaply with granny grating, plascard or other bits.
Modded pieces across from their unmodded bretheren
Bits applied.
Saved the helipad for future projects.
Sprayed the roof grey and core building straw yellow
Assembled, base colors painted, a light brown wash and done!

Haven't yet decided how, or if I will base it, but I'll definitely be on the lookout for similar toys in the future.
Being a Micro machines toy, this is best for 6-15mm, but Matchbox or Hot Wheels toys could probably work for scales from 6-28mm depending on what bits are applied.