I have been making bases and molds for most of the day, and decided to make an epic base for my Vessel of Judgement.
I usually use Milliput for my sculpted bases, but I gave Sculpy a try this time. The advantage of Sculpy and other polymer clays is that it doesn't dry out, so you can take your time adding details to a base without rushing it. That is especially helpful on a 120mm base. Another advantage of polymer clay is the price. It is much cheaper than any of the epoxy puttys, and more readily available.
The disadvantage of the Sculpy is that it has to be heat cured. You cannot sculpt a base and then put it in the oven to cure the sculpy...don't ask how I know that. The only option is to hit it with a heat gun a few times. Be careful with the heat gun, if you use it for too long you can melt the plastic base....don't ask how I know that either. Your best bet is to use the gun on the sculpted base for 30 to 60 seconds and then let the base cool. Repeat this process until the clay is properly hardened. It took 4 passes with the gun before the clay was hardened enough on this huge base.
Even with the cons, the base turned out well. I think polymer clay will become another weapon in my nerding arsenal!