I've wanted to make hot pads for gifts. I was thinking to do a single block, add a border if it needed to be larger, and then quilt it and bind it or do the envelope/birthing method to. I would use at least 3 layers of cotton batting, perhaps with one layer of those being insulbrite.,
Another idea would be an ironing pad, with the silver stuff for one side, then a layer of insulbrite, then a layer of cotton batting, then the other side. There are some patterns for these which double as a hot iron holder.