I plan to order some glycerin and molds to make some soap. I am wondering though about measurements. The glycerin is sold in 2# blocks and the molds I have in mind are four on one sheet and each mold is 3.25 X 2.25 X 1.5. I don't know how much of the 2# block I will need to make each set of 4 molds of soap. I am sure once I get going I will be fine but I want to make sure to order enough supplies to start. Thanks!