Mike F.:
This probably falls in the Craftsman area, butttt here's what I use:
A short piece of doe skin with a slit in one end. The other end is looped around trigger guard and through the slit. At that end, I use a spent .25Auto casing, cap removed, drilled and tapped for short brass screw, which goes through the doe skin.
It fits nicely over the cap and nipple; with the hammer down it serves as my safety and my moisture protection. It's important to note after full cock, remember to remove protective casing as it may not automatically fall off.
Osage