ya I've heard of guys making their own soda blaster. I was actually going to try it to blast my carbs, already bought the baking soda just haven't tried making the blaster. Your right though it won't alter the substrate it will only clean. It would take off dirt and paint (might be slow). I went with blasting because I wanted to etch the surface for paint.
xschris- that appears to be a glass bead finish. I don't think plastic would have etched it that much.
Shaun