In vacuum forming, you heat a sheet of plastic until it is completely flexible, then stretch it over some kind of form, and vacuum all the air out so the plastic sucks in tight against that form. When the plastic cools, it retains the shape of the form. I wrote an Instructable about the homemade vacuum former
I was using.
To make the rupee form, I used a piece of oak I had in stock. I wanted something hard that I could get clean lines on. I cut the shape out using my table saw, then set the blade at an angle to cut the bevels into the edges. It only required very minor sanding to clean it up.