I used air dry clay here, but you can use polymer clay, which is a bit more weighty. The magic trick is the Perfect Crafting Pouch from Scraperfect which is a fantastic stamp release for any of these clays.
My stamps included wood mount rubber stamps and some vintage buttons – which may have given the best results. I used alcohol inks and an acrylic sealer.
Tip: Make sure your hole is big enough for whatever cord or chain you want to use! I had to enlarge my holes a little.