Aluminum Pet Cooling Pad for Bunny, Cat, Rabbit, Hamster, Guinea Pig and Other Small Pets, 11.8" X 7.9" Summer Animal Cool Mat Plate Ice Bed Cage Accessories

Something like that will also work great! I would do aluminum though, as its a better conductor (will draw more heat from peegs) and 'recharge' faster. Plus I think theyre cheaper. Here is one on amazon as an example: https://www.amazon.com/WELLYUK-Aluminum-Cooling-Accessories-Hamster/dp/B0BTL96QL5?crid=3FAJ8I39CSYHU&sprefix=aluminum+cooling+pa%2Caps%2C157&sr=8-8