I found a YouTube video of a guy using this stuff, and wondered if any of you have tried it.
(I did a 'search' and tho' several posts came up, none were about this material -)
It is a kind of gel used to build-up a body, and you can shape and blend colors.
In the video he is tying a kind of streamer fly, but I can maybe see this used for jigs too... you could put a fat belly in a jig, for example.

Video link
YouTube - Fly Fishing Tying Demonstration - EZ Sparkle Sand Eel Fly