I have small confession to make...
The space blanket I've been using is not 20?m thick as originally assumed. It is actually just 6?m thick! I got hold of a proper micrometer today and was able to measure it far more accurately.?
So, single-side metalised 6?m Mylar is available in sheets of 100cm x 150cm, (folded into 10cm x ~7cm rectangles) for a few pounds each. If you don't mind edge-terminated I can't imagine a cheaper way to make condenser capsules!
