Ordered silicone cast form, bought a crockpot (worked 10x better than i hoped it would for melting) and starting casting my own wax bases. Pretty satisfied with them. Yes, I know they are not rectangular ....but i did not want the form to overflow or the sheets become too thick. I need to cut them a bit anyway and Like all beekeeper mistakes : the bees will fix it.
I just shove wires into wax with some two-pronged hard implement (to push on the sides of cell ridge).
I've also tried using woodburning iron to melt a few spots of wax to the frame, it worked amazing (and cutting pretty honeycomb from the frame was never easier), but with one catch: if wether is hot and bees are slacking, it deforms faster then they reinforce it and wax rolls off. These frames survived my centrifuge too, the trick is to make syre bees attach it on all sides by, well, tack-soldering on all sides indeed. Will not work with op's casts and centrifuge though.
Was thinking for a year that casting flat wax and then rolling it with patterned roll press might be better idea. Anyone tried that?
I considered rolling but wondered if it would not stick to the roller easily. Then again, it's not uncommon. This just seemed easier and more affordable. Buying Form + cooker was less than €60:-