Found a cheap sleeping bag mat at Wally World for about $7 bucks. Cut it to fit the scope, might cut it lengthwise now too as it's a little long, but we'll see. I think this material will work out well, it's waterproof, slightly insulating and very, very light.
Used 2 heavy duty velcro patches to fasten it into the tube shape around the scope. These seem to hold it on really well with no need for any other fastening device. We'll see how it holds up to a field test soon.
For the inside I hot glued some black felt to reduce light reflections, scattering, etc. This is the part I'm slightly disappointed with at the moment, the felt doesn't sit very flat on the curved surface, and bunches up in places. Don't think it's bad enough to block any light entering the scope, but I just don't like the messy look. As a note, super/gorilla glues will NOT work for this project. They only get absorbed by the felt and don't stick to the mat. Hot glue holds it on there pretty well.
Next project is the dew heater/controller. I've already made the heating strip, working on the controller now. Will post when completed(or at least closer).