I may be the last person on Earth to know of this company, but Plastruct, Inc. has just about every kind of material you might ever want for model building. They specialize in plastic shapes and textured sheets, but carry everything from basswood to clear acrylic balls. Download the catalog. Check it out. Plan a scratchbuilding extravaganza. As a bonus (or minus, depending on your memories), the catalog is very 1980s.
Here’s the link to their website.
Here’s a direct link to the PDF catalog.