Belive it or not, squirt guns. Keep an eye out in toy stores or just the big box places. I have a squirt gun (in orange) the correct dimentions for a glock, another (yellow) of a 1911A1 and a third that passes for a Colt Python (That one is red and yellow)but will work well for most .38/.357's.
As for tools I use to wet-mold a new holster, I wet the leather, work it with my hands around the mold while watching a movie. for more definiation, I use a wooden ice cream bar stick, and a piece of dowel rod I sharpened in a new pencil sharpener on both ends.
Luck