More Homemade Kitchen Artwork

This project needs a bit of work. I made it just last night. The frame is a $10 shadow box frame from Ikea. I covered the mat with leftover kitchen curtain fabric (photos coming soon once I get the bay window rod). I then attempted to attach or hang some copper cookie cutters from my mom, who got them from her mom. I didn't want to hot glue them because I didn't want to ruin them. I put tacks in the mat with tape on that to try to keep them on there. Next I might try some of that yellow tacky stuff that you can put stuff on the walls with. Any other ideas that wouldn't hurt the cookie cutters?