heated print bed for RepMan

So here is my attempt at a heated printing-bed for the RepMan.

power:
I found these 37W heating-pads and a matching 120W power-supply
that I can manually regulate between 15V(62.5%) and 24V(100%).
I´m not using a temprature-probe to keep a target-temperature yet.

surface:
I´ll try to attach them to the underside of a copper-plate.
Experiments of other people have shoan ABS to still reasonably well to copper but very badly to aluminium.
If that does not stick I can always get KaptonTape for the surface.

mounting:
To isolate the plate against the temperature-sensitive polyacrylic-parts of the RepMan I´m going to use a ceramic wall tile like prusajr did here.
But I will not keep it in place using clamps but with screws, oversized, long holes for these screws and large washers.


thermal expansion:
That should allow the copper to expand in XY-direction so it does not expant too much in z direction while not interfering with the cross-supports of the RepMan during movement around the z-axis.