Or: what I did this afternoon.
My design for the plates, hot off the presses. Note the patterns on one side, combined with holes completely through the plates. The large hole in the triangular bottom plate is where the tubing will connect:
And here it is folded, just before ironing:
Aaand after ironing:
It hasn’t quite transferred properly at the top right on this side (the reverse is fine), but that is easily fixed with some enamel paint, which I’ll acquire tomorrow.