Polycraft FC7450 Back-Fill Polyurethane Liquid Plastic Casting Resin, Durable, Easy-to-Use Mould Making, Resin Casting Material for DIY Projects - 1kg Kit

I was expecting a rubber finished product with 70 shore hardnes, or tough rubber. But this dried/cured to a hard none giving block. If you applied this as a filler to your mould it would become inflexible & brittle. Not as I was expecting. So a waste for me. The hardened material is easy worked with cutting blades or sanding. Dried colour was custard not brown. Consistency when mixed was thin gravy like. It found many holes in my mould & readily drained so be careful to protect surfaces from leaks. It sticks like the proverbial to a blanket, which was part of what I needed. But easily released from properly prepared surfaces (oiled or greased etc). You could machine this dried, cured block. But it is not rubber.