This tutorial comes from Roots and Wings. They offer a great step by step guide to pouring your own urethane molds and then using them to create Lego soap. The urethane mold could also be used for other projects: chocolates, ice cubes, playdough, gummy candies, etc. Note: if you use the mold for making food be sure to get the urethane that is approved for food. Thanks Rebecca!
(Images: Roots and Wings)