Hi there,
has anyone tried out one of these little helpers? I've sent an etched PCB to a friend who sent me a black styrofoam ball cut into half and said it would take the sharpness out of the sound. Seems like a brilliant idea to me. Are there any DIY instrutcables somewhere ?

Ted Weber makes 'em (or used to). In fact He registered 'beam blocker' as a Trademark.
I have heard of people just using Duct Tape (gaffer tape/cloth tape) as a beam blocker: just put a single strip across the speaker - Much cheaper that way.