Oh, and I'm using a glass tabletop for a bed. 600mm diameter. About USD $40 from Amazon in the US. It is about 6MM thick, This makes it fairly flat (you can glare light off the top and the reflection is not distorted much, if at all). The heater works very well through that thickness. Heater was custom made, about USD $220. I just used the adhesive it came with and stuck it on the glass.
0_1552491279671_IMG_2026.JPG
The glass is only supported at six points, and smart-effector mesh maps typically look like this:
0_1552491562636_Bed Mesh.PNG