This is an excellent question, but I haven't responded earlier because I must admit I take a "head in the sand" approach and just put cars and parts in various showcases and boxes, even in piles (for incomplete cars/junkers in the boxes), without paying much attention.
So far, after 15-20 years of collecting, no apparent damage, but I did do one very stupid thing. I had one of my vac-form cars on a bookshelf for several years, with a halogen light not far. By the time I realized my error, one side of the body had already started to curl away rather flagrantly, and that's almost impossible to cure...
I know it's not ideal to leave cars unenclosed like that, but have run out of protected spaces....
Don
So far, after 15-20 years of collecting, no apparent damage, but I did do one very stupid thing. I had one of my vac-form cars on a bookshelf for several years, with a halogen light not far. By the time I realized my error, one side of the body had already started to curl away rather flagrantly, and that's almost impossible to cure...
I know it's not ideal to leave cars unenclosed like that, but have run out of protected spaces....
Don
