Steps:
- Connect the vacuum pump to the vacuum nozzle with a rubber tube. Make sure to securely attach the tube to both ends so there is a perfect seal.
- Insert the ping pong ball into the firing end of the tube and let it role to the rear end where it is stopped by the base of the nozzle. Make double sure it is as far back as it can go
- Apply packing tape to both ends. make sure the packing tape is firmly attached and that there are no leaks. Only use one layer of tape at the front end (so its not too strong for the ball to break through it) but use two at the back end to be safe.
- Turn on vacuum pump and listen to see if there are any air leaks. It there are seal them with tape. Having an air tight seal is very important!!! It will not work if there is even the slightest leak!
- Once the pump has achieved the lowest possible air pressure (for me it was around 11.6psi), pop the rear tape with pin. This will let the outside air, which is at a higher pressure, flow into the tube and push the ball down the tube and hopefully firing it out the other end.
- Plug your ears and watch!