Good stuff ripster. I've done a good deal with bead blasting cabinets and have one in my garage. I first used one when restoring a 67 cougar with my grandfather, it was my favorite tool. Amazing how an old rusty part can look like new coming out of the cabinet. Now I use it for hobby related things.
If you want to mask/stencil something off, use quality electrical tape, taking care not to stretch it, just apply it and rub firmly into place. If you stretch it it will "walk" on you and the edges don't seem to adhere as well. Use a clean new roll that doesn't have gunk on it's edges from the bottom of a toolbox for best results. Blast straigh on, or at an angle that won't peel up the edge of the tape and you'll be fine. It's rubbery enough that the beads bounce off of it rather than penitrating it.
But caution to anyone thinking about this, it's addicting.
This yo-yo was black anodized aluminum:
After some electrical tape and bead blasting, it looked like this:
Note the edge where the tape was is very sharp, no peeling back or roughness there.