epoxy

• Epoxy fillers are incredibly handy, as they let you dial in the desired level of thickness.
  • If you don't have any proper thickener on hand, you can use any fine powder. I've used baby powder before, and it worked great.
  • Ideally, porous surfaces should first be wetted with un-thickened epoxy, before adding the thickened epoxy on top.
  • Silicone can also be thickened via cornstarch and other fine powders.