Paintball-sized foam balls, the same mass as standard garden-variety welt-making devices. Contains 6 orthogonally-oriented leds powered by a small battery.
Mix them into your hoppers, but not until you pull the plastic interruptor out of each one you intend to use - thereby allowing the circuit to be completed and powering up the lights.
Not recommended for nighttime use if you have a clear paintball hopper - your gun will light up like a christmas tree. A christmas tree that wants to be shot.
(Edited to refine circuit breaker tech)-- shapu, Nov 18 2007 The Inspiration Paintball_20Tracer_20BulletsThis idea by [rascalraidex] is probably cheaper. [shapu, Nov 18 2007] Baked for a different sport ... http://www.twilighttracer.com/Reuseable, activated by impact. [batou, Nov 19 2007] I thought about LED's, but I have an affinity to glowsticks from raves in my past.-- rascalraidex, Nov 18 2007 Six of one...-- shapu, Nov 18 2007 Glow sticks are the way and then your enemy will be easier to hit again, but do people really play this in the dark?-- MisterQED, Nov 19 2007 random, halfbakery