I used a plant germination heat map on my desk to have some warmth for a while, in a not well insulated room. It was mild help but nowhere like this. I'd really hoped it could help keep my hands warm, make the keyboard warm, but even letting it run for hours didn't do that much for the keyboard, and it's not like you maintain ongoing contact with it.
Cool to see this write-up. Nice to know there's a somewhat more sophisticated path available, with these carbon heat foils.