The gelli plate's first incarnation sort of worked, in that it didn't work! It set - good. It stank - bad. It split - bad. I needed more gelatin to hopefully sort the problem. The only gelatin I had though was leaf, but I had quite a few sheets. I don't know what the powder / sheet equivalent is, so I melted the lot! Remelted the first gelli plate and added all my gelatin. This time, it set REALLY well lol. Still stinks. Didn't split. But not all the sheet gelatin was fully dissolved and I had a few air bubbles. Anyway I had a play - I used copy paper rather than card, just to try it out, and some cheap acrylic.
I think in all, it does what you'd want it to do, the paint stays open long enough, and goes on quite smoothly, The only real drawbacks are the smell, from the surgical spirit (rubbing alcohol) and it has a slightly oily transfer.