what is a goods mud alternative? iv heard joint compound, clay , and pottery clay are goosd buyt just not sure what works best

I'm in the process of producing a custom with this stuff: http://www.bentoniteplus.com/instructions.html

I can let you know how it turns out! You'd just have to remind me in about 2-4 weeks, haha

Bentonite clay, for sure. We have over 250 gallons of it in a tote for sinking pleasure.