I use mostly new materiel, sheet balsa and styrene, but i do use bits and pieces as well.
The brass machine guns on my mad cats are female pins from an old RS232 computer cable plug as an example.
The chest plates on the BK's are cut from some old self saucing pudding containers
The nose of the daishi is a clear plastic deoderant cap
The sat dish on the atlas is a brass thumb tack etc etc
Building say a goliath wouldnt be any harder than any other chassis, but to be honest i never really liked quads even back in the CBT tabletop days.
I did once look at a train set diorama with a view to using it to display my collection, but 30 plus mechs and vehicles as well it would take up a lot of room.
My collection of Sci fi models has been offered to and accepted by the local toy museum when i croak, and it features a large collection of train sets. So its not impossible that they may end up being displayed in that mode eventually.
That day is (hopefully) a long way away, but the plan is to fund the building of a wing to house my collection, and i plan to canvas the idea when that time comes.http://toyandrailwaymuseum.com.au/leuralla-toymodeltrainailw.htmlhttp://toyandrailwaymuseum.com.au/leuralla-collectableanttoy.html
Here is a build thread which will give you an idea of what goes into making onehttp://forum.mechlivinglegends.net/index.php/topic,15544.0.html