Using the section of Caravaggio's painting (below) I have attempted to sculpt the hand of Saint Thomas out of polymer clay. Because of the size of the hand I didn't need to use wire underneath as support before putting in the oven to harden. 

After the hand was baked, it was hard enough to make a cast from. I first tried to dip the hand in alginate as if a normal hand cast, however this didn't work as it was too small and flimsy. My only other choice was to make a two part plaster mould which could then have wax cast inside.  

I soaked the plaster moulds in water for around 10 minutes before placing the two halves together to pour in the wax inside. After letting the wax cool I pulled the halves apart hoping to have a perfect wax cast. This was unfortunately not the case. The finger was so small and fragile that it broke off every time I tried to cast it. I was able to stick the finger onto the hand using a hot tool which could melt it together.  This melting and sculpting worked fairly well, however it kind of defeats the purpose of having exact casts of the original sculpture. I need to think of an alternative option. 

---

Hand of Saint Thomas, Wax

My next idea was to simply press my sculpture into some soft clay (both halves) and then fill these with melted wax. Then I'd just have to fuse the two halves together. Again, the index finger was far too delicate when trying to remove the wax from the mould, despite it being maluable this time.