Take 2 equal amounts from each side,
Mix untill all one colour, and no streaks.
Use a little bit of water so it dont stick to you or tools,
Mounld it onto what ever you need to do,
Allow to start setting off ie 3 hrs
Trim a little with sharp knife if you need to
After 24hours it should be hard and then you can sand, tap, drill or cut it

Hope this helps