Assess the size of the acting area. If your stage is relatively small, you will be able to get away with linking two to three instruments, whereas a 12-foot or wider stage might require more. Decide whether you want your black light to be a permanent fixture for future performances in order to make the best choices in lighting placement.
Purchase an adequate number of "shop light" fluorescent fixtures to fill your stage with the black light. These are stand-alone units and will typically sell for around $9 each and require very little electricity. Purchase the corresponding number of fluorescent black light tubes (as the tubes require a mixture of special glass and paint material, it is considerably more affordable to just purchase them).
Decide on the location for placing your light fixtures and visualize possible lighting angles. For some shows it may be more appropriate to simply rest the fixtures on the ground in order to shine up onto the puppets, creating a stark dramatic effect. This option will decrease how much light you get per lamp, however, and may require additional fixtures. If there is adequate space above the stage a common option is to hang the fixtures with chain either directly above or slightly in front of the acting area.
Screw in the fluorescent black light into the shop light fixture, being sure to keep the unit unplugged while doing so. If you plan to hang the fixtures, secure lengths of chain to the clip units on the back of each shop light and raise it to the desired height before attaching it to the ceiling hang unit (usually an eye-hook screwed into a stud in the ceiling, or an I-beam).
Connect all the fixtures to each other with a multi-head extension cable or adapter. Run the cable to the adequate light source (if plugging into a dimmer, make sure the dimmer is "hot-patched" or always on, as the fluorescents are incapable of dimming).
Test your new black lights while turning off all extraneous light on stage. Remember: the wattage from the tubes is relatively weak compared to the average 500 watt stage light, so you will need to create relative darkness on stage to see the full spread and effect of the black light. Practice adjusting the height and angle of your fixtures until you are satisfied with the desired look.