I made a video but I lost it.
I did my first test on the actual bed without heat and with a layer of painters tape. First problem that arose is that the bed still has too much flex in it. The current bed has poor guidance, so that will be fixable. 3 more obvious problems showed themselves.
1. Once the printer started printing, the spot beneath the printer became warm. I don't usually run the fans the first 2 layers, so it expanded. This caused the part of the bed where I was printing to bubble up or down, with a notable ping when the printer pushed it down.
2. The painters tape has too much adhesion. The part stuck more to it than the adhesive of the tape itself. Once I pulled the part past the bend, it just went over. It required considerable force to pull the part off. I will try on kapton next, because it has less adhesion to the material.
3. The part had a notable warp to it. This may be in part the current flex in the bed, but also is because it is not stiff enough.
I am thinking of making a mechanism that lifts under the flat portion of the bed. This mechanism can use vacuum to pull the bed flat to it, and may have aluminium contact strips that force the bed flat and heat it. One thing I do know is that my current setup requires some more work.
Good ol' plastic extrusion