I stored them in carefully labeled envelopes so I was ready when I wanted to make the quilt. Some were too big for small envelopes, so I stored them in the larger brown-gold-buff (or whatever you call that color) envelopes that I could fine at the stationary store (there weren't any office supply stores then.
A definite improvement over gluing sandpaper, x-ray film and tracing paper together, though they didn't stick to the fabrics that well and could move while being traced. This also didn't allow you any leeway in making size changes to the blocks. You had to cut the lines straight to assure your pieces were straight. Being the obsessive-compulsive quilter I am, I used a metal edged ruler and exacto knife to cut mine.
Obviously I never used some of them, as they were never cut out.
How many of you quilted with these things too? I'd love to hear your memories - either in a comment or a blog post of your own.