i will explain how they work to the best of my understanding. i have taken one and cracked it open and studied the electronics a bit. i apologize for the lack of illustration, but like i said, i will take pictures once i get this working.
it looks basically like a christmas ornament in shape and is red acrylic and striated, kinda like brake lights might be. the top part has a screw-in cap that has a plunger and a spring inside. it screws onto a cavity that contains 2 lr44 batteries, 1.5v each, and 3 contacts. there is a spring at the bottom for the - contact and there is a bent wire that runs in a channel along the side of the cavity for the + contact. there is also a 3rd contact at the bottom. when the plunger pushes the batteries down, this 3rd contact turns the electronics on and off, in essence acting as a momentary contact switch.
when it is on, the 4 LEDs flash in a sequential pattern. they will continue to do so until the plunger is pressed again. the LEDs are attached to a small circuit board which also contains leads for the 3 contacts, a 0.47uf capacitor, and a small IC covered by that black stuff. from my rudimentary understanding of electronics, the cap keeps the circuit open even though the batteries are always touching the + and the - contacts. i assume the chip somehow uses the 3rd contact as a trigger.
the top half of the ball is mostly taken up by this cavity for the batteries. the circuit board mounts driectly onto this part. the bottom half is just a hollow dome, which gives me space to fir the radio shack button.
i have been using one for testing and tried to keep the electonics complete. i used a GameBoy AC adapter for 3v of power and figured out how the 3rd contact worked. i then tried to see if i could get it to turn on automatically when powered by connecting a cap between the 3rd contact and the - contact. this worked fine for a minute or so, but eventually the sequence would break down to only 2 LEDs flashing. so i decided to scrap this idea and harvest the LEDs and wire them in separately and just have them on continuously.
i also had a very hard time getting the ball open. the halves seem glued together. i tried a hairdryer but the plastic began to warp and they were still stuck tightly. i had carved a 0.5" hole for the button and tried nail polish remover and then ethanol along the inside of the seam but ended up damaging the acrylic. i guess for the ones i end up using, i will avoid trying to open it but rather try to crack the circuit board and take it out of the 0.5" hole in order to get the LEDs.
I did consider other options for ball tops, but these pet strobes were the best candidates i have found. they are translucent and red, they are the right diameter for the most part, there is just enough space for the top fire button, and the battery cavity will fit the shaft. i found them for $5 at Bed, Bath, and Beyond while looking at acrylic finials there for this same project. i know that Tom had just started up again and his balltops would look much nicer and may possibly be adapted for LEDs and a top fire button, but there is always something to be said for DIY.