OYUMARU is a fantastic material which can be used to easily make molds.  All you need to do is to warm the OYUMARU either in hot water or on a hot surface.  Then press the item for which you wish to create a mold into the warm OYUMARU and you let it cool off.  You then take the item out and your mold is ready!  If it is not up to the standard you would like, you can warm it again and try again.