The other side looks a lot more promising:
A closeup shows that the characteristic 3D printed striations came through perfectly on the silicone:
In this application, the 3D printer’s hand-knitted look is desirable, but most molds would benefit from manual smoothing / sanding / filling; perhaps slathering release agent over the molds would help. In any event, the silicone didn’t lock to the striations and parted easily, so it’s all good.
The first layer of silicone worked its way between the positive molds and the slab; Tesa says the positives were so well attached to the pegs that she forgot to apply double-sided tape between them. No harm done: the flashing peeled / trimmed off easily enough.
She thinks a shallow block mold would work just as well for a slab like this: you’d (well, she’d) save hours of tedious layering. The block mold wouldn’t use any more silicone, as the mixing cup had plenty of residue after each layer, even after scraping: doing just one mixing, one pouring, and one curing stage would be a major win.
She also knows how to melt and pour chocolate…