we used to get a shop vac and set it on "blow" and then point it upwards with ping pong balls floating above it. It takes some time to get it perfected, but its fun...just dont shoot the shop vac.
Also, for our league one night, everyone had to shoot mathews genesis bows (no sights, no releases). 5 arrow ends, but shot at the big circle on the back of the 5-spot targets.
2005 Hoyt Vtec 28/70