The "gel" I used is Clear Tar Gel. It's an acrylic medium made by Golden. I get mine at dickblick.com, but Michaels also carries it. I'm guessing most fine arts stores carry it. It's a thick, stringy gel that is perfect for creating a "surface", almost like a fruit roll up, but not sticky (and not even close to edible!).
I use lots of fine arts products when I'm playing - the velour paper, the acrylic mediums, the pencils and canvas paper. I have always been a freak about art supplies, but just never knew what to do with them. Now I do all kinds of really cool stuff with things I never even knew existed. I have a garnet gel, an acrylic medium with red sand-like stuff in it that can be used to create a "rusted" surface. I think I've said this somewhere before, but if there's an obscure product out there, I probably have it and have been trying hard to figure out what to do with it. :o)
Tar gel is really, really cool stuff. I only got a pint. I need to order a gallon.