Hi samwl, thanks for the response. I agree that something that stays in the palm / fingers does restrict – I would love to find a way to have something like a little pad on each finger or fingertip but keeping them durable and attached is one of the issues, as is heating five separate areas.
Unfortunately, the silicone I used needs a very good amount of energy to heat up. At first, I wrapped it around a hot mug and that was insufficient. With a heat gun, it stayed warm for a bit and was very evenly heated, but a heat gun is a little much!
I have taken a little time off this project to clear my head and hopefully find some inspiration … it wasn’t coming when I was hitting my head against the wall. 
I took a look at the link to the video of evenly heated fabric that you posted, I am thinking of going a soft-goods approach (and people joked that the metal design above could’ve been some kind of vibrator 
).