some are plastic models that were available back when the tabletop game was the game, the LAMs shadowhawk, griffin thunderbolt ,stinger and wasp were plastic kits, the others i made .
here is a pair of half made loki's to give an idea of scale

not quite as tall as a BT novel, about as tall as a cola can

some final detail before getting their skins

My mates ran lots of the plastic models, so i started building these to give me some tactical flexibility, they do take plenty of time to build, but it doesnt take long to get the hang of it, balsa wood is very easy to sculpt, and model shops sell all sorts of plastic strips angles and I beams , which make the detailing easy enough
you can always look out for older robotech toys as well, many of these are suitable for larger scale play, we would play in the even larger scale with the riffleman and warhammer toys that were available
http://www.toywiz.com/rommoki.html