As a VW owner, I've been using PlastiDip for mods for a while now, and I have to say I LOVE this stuff. I've never used it on keys, but can give a few general tips about the stuff.
1. Lots of thin coats = grippy more textured surface
2. Few THICK coats = shiny, smoother surface
3. After curing, spray with 303 Aerospace Protectant to "condition" and help prevent dust / fuzz buildup. I use 303 exclusively for all cleaning and wiping of plasti-dipped surfaces.
4. To remove, find a corner or edge of the material and rub VIGOROUSLY with your fingertip until the surface heats up and the plastidip starts to roll off the surface. Once you get a loose edge, just peel away.
5. USE IN WELL VENTILATED AREA AND WITH A MASK! This stuff is pretty nasty as far as fumes, and has left me lightheaded and with severe headaches many times.
6. Use the spray and the dip cans wisely for specific jobs. This stuff can even be thinned with Naptha and brushed or rolled on. I use the dipping cans whenever a smooth uniform finish is desired, the spray for a more flat, textured look. The dipping can also goes on MUCH thicker if not thinned, so is ideal for protective uses.
7. Use caution when recoating. Applying a new top coat softens, and can even liquify the lower coats, so handle more gently after recoating than you did on the initial coats.
8. Colors can be mixed, but do so on the front end, IE with the dipping cans. I haven't been able to get a finish of any value by starting with one color and then spraying a 2nd color on top. I wouldn't even use a second color to try to cover up the first, for reasons mentioned in #7. The bottom color will bubble up through the top.
I'm sure I'll think of more, but thought I would throw this list out to those of you planning to start using the 'DIP. The finish is very nice and holds up extremely well, even on automobile exterior pieces exposed to the elements, but can be easily be removed with enough friction.