I did think of the idea and searched the net and I did find the product available. As it turns out, making the item is pretty easy!
If you would rather order them I believe you can get them via Amazon for about $7.50 shipped (believe this is for package of 16).
Step 1: What You Need
- Foam rubber floor tile material - I used 5/8" thick variety. You won't need much!
- Double-sided foam tape. Mine was 1" wide.
- Utility Knife
- Drill and drillbit - I used a 1/4 inch bit.
Step 2: Cut Foam to Size
Step 3: Drill a single hole.
I believe you could probably avoid the double drilling by just using a hand-held drill.