I added a layer of batting as well as the insulated fabric which was the very thin silver fabric with no batting.
When I saw photos of everyone's adorable mug rugs I knew this would be the perfect solution for me. I had nice tile coasters which didn't absorb the moisture from cold drinks. But the coaster would stick to the bottom of the glass....and... when they hit the hardwood and slate floors, didn't last very long. These can absorb moisture, are heat resistant and when they hit the floor... no big deal!! ;-)
Plus, it was so much fun making them and they match my room! :-D