I've had fun with a few new art obsessions lately. One is painted deli paper. I've used deli paper for years, it's a great substrate. You can paint on it, print on it, stamp on it, and then incorporate your papers into your mixed media pieces. I taught a class this past weekend on painted deli papers and we had TONS of fun.
Deli paper is just dry waxed paper. I buy it at Costco, but this link from Amazon will show you what it looks like: Dixie Kabnet Wax Dry Wax Paper Deli Wrap 12" x 10.75" - 2/500 ct.
This page has painted deli papers as well as some hand cut masks:
This silhouette has a painted deli paper dress: