Man....these restrictions are getting annoying. The interface is a bit annoying too, but such is way these things usually go, so I'm not detered. Right now, I am working my way through the turrets and I'm going more for functionality rather then entirely look (really difficult with the big guns):
Well, that turret idea wasn't working out the best, but I found a better building mode and managed to up with this beauty for the turret (for some reason I could find any good "roof" pieces that were long enough so I improvised...and quite well I must say. Well now that the turrets are ready, I'll start on the skeleton.
I'd love to see this when it's finished. Good luck! BTW I noticed that sometimes a if a part is listed as unpurchasable, you can just change the color. Might throw your color scheme off a bit, but I think keeping the proper shape is more important.
Well, I spent some time on it and now I have the middle bar finished (barring some color changes) and part of the top of the center tower done....complete with BAT (big a$$ turret).