found a rather inexpensive 100mm lensball from neewer for only $15 US.
let the fun begin! the only thing is I don't have a tablet which I'm guessing has a different display because my computer tends to have grid lines close up. I know some use a tablet or ipad.
This is the one I got. Pretty large so it's a bit heavy. I don't think I'll be carrying around a lot so I got the bigger one!