Once the sculpt was done, I just hot glued it to a plastic foam board base.
It's looking a little shiny here, that's because the first coat of DragonSkin silicone has been applied. It was brushed on to make sure it got into all the little nooks and divots and whatnot.
And just for some additional information. The sculpt was done with Monster Makers Premium Clay, from Monster Makers. The moulding and final casting materials all came from Smooth-On, purchased here in Canada from Sculpture Supply and Sial.