Some of you asked about how I made those marbled gloop tiles a couple years ago.
You could use a gloop recipe (link below) or just colored slip.
After making a batch, add 40% water by weight. Blend at high speed, then slowly add a deflocculant like Darvan or sodium silicate until the mixture is the consistency of casting slip.
On a plaster slab, pour out a fairly thick layer of the mixture. After it’s set for a little while (but still wet & shiny on top), use squeeze bottles to apply designs of different colors. Then use a toothpick, needle tool, comb, or other marbling tool to make your design.
Wait until the top layer is no longer wet or shiny. It will “frost over” like an icing lake. After a few more minutes, you should be able to gently lift off the slab from the plaster.
For these marbled gloop slabs, I laid each on a porcelain slab base, but I also spread silica sand on the kiln shelves just in case. I was in a rush and very impatient, so the slabs cracked while drying. I’m sure you could do a better job with more time and better technique.