[Skoob]

I don't believe I understand your question either. If you're concerned about thumbtacks damaging your card backing, you might consider plastic reinforcements like these, which are a common item at retail merchandise supply stores.

If you don't want to put holes in your wall, you could pick up some adhesive 3M "Command" hooks available at any hardware store, but the cost for a large quantity of those might be prohibitive. Thumbtacks or small brass picture-hanging hooks with finishing nails strike me as more economical and sensible. Best of all is plain ol' plastic thumbtacks.

If I had a large collection, I would be inclined to confine the display to a limited area with minimal traffic so as to reduce the chance of anything being knocked off the wall, and rotate the displayed items whenever it suits me.

Beware of sunlight! Even a small amount of indirect sunlight can fade color and turn plastic brittle over time.