Did not check it out yet, but i have been waiting for this!
Do you think, it would be possible to make transparent hands also?
Could you color the guns according to the icons (grey pistol, white chainsaw, red shells, orange rockets, green bullets, cyan grenades, blue riflerounds)? Cannot tell from your description or the screen ...
10/10 for getting this idea going!
Edit: I second Suicizers idea about a black outline, or wait: a solid outline, but in the same color as the model.