Mine were regular negative size. Today I saw them in so many different sizes. Anyhow to cover them I cut a 2 1/2 inch square of paper of my choice. Then I centered the negative drawing an X in the center from corner to corner. I then picked up the paper minus slide frame and cut the X. Using temporary roll on glue so negative frame wouldn't slip I recenter the frame. Folded the triangles from the center of frame trimming any bit that hung over outside edge and sticking them down. Then I folded outside edges over sticking them down. I cut a vellum saying to stick in the middle and then stuck the whole thing to another 2 1/2 inch square for matting. Am I making sense? It was fun and easy and now I wonder why I haven't done it more.
Lynne