How can I make my arm look like the Sandman?

Hi everyone!

Ok here's the deal. I'm going as Sandman this year (as in Marvel Sandman, not Gaiman), and for the sand part I've taken one of those Hulk fists (the kind that's a glove you put your hand into) and put some adhesive on it, so it looks like a giant sand fist. That part is going great.

The tricky part is that my shirt is short-sleeved, so it's going to be a sudden change from the skin on my arm to the sand-fist. So I'm trying to figure out how I can make my arm gradually become more and more sandy, to ease the transition from skin to sand.

Any ideas on how to get sand to stick to my arm and not fall off throughout the day, but come off easily once I'm done?

Thanks!