Battery adapter made from smooth-cast 325 urethane resin.  Size AAA to AA, AA to C, C to D.  Also shown are the GI-1000 silicone molds.  They are finished by inserting a 6-32" brass screw into the holes cast into them.  A solid piece of resin was turned down on the lathe to make the first set.  They're not for a specific project, but I've found sometimes on set you need a battery fast for something and just don't have the right size.  There are the obvious day to day uses as well.