I bought a moderate amount of silnylon from a kite maker and adhesive tape from a sailmaker. I also have several yards of silver mylar that is quite thin & light.
It occurred to me that I could make a lightweight / warm reflective top blanket by sandwiching the silnylon & mylar together with the sail tape. I'll probably fold and sew the nylon over the mylar around the edges.
Used by itself, it would generate a fair amount of condensation. However, I sleep with a vapor bag inside my sleeping bag, so vapor build-up should be minimal. Along with keeping warm, my aim is to have the sleeping bag insulation kept dry between 2 impervious layers.
Wonder if anyone has tried the same and whether they found it durable / useful?