if its cool then there is always some kind of danger. most of it not life-threatening so long as you have common sense.
a "cool" but pointless magnet shooter thing would be a coil gun.
you can build a beginner's model with a photoflash camera's internal circuitry, a homemade coil, a straw, and some nails. its not a dangerous gun, so long as you don't look into the barrel while firing the gun. you can shoot nails and BBs about 30feet at less than 100 feet per second. I built a beginner's model also, It cost me about $30.
here's some info about coil guns:
with a simple single stage coil gun its not very powerful or effective. you can try to build a much more complicated and exponentially much more cooler multistage coil gun after the beginner's model, or look to build a rail gun, similar to the coil gun but but much more powerful, fun, and has a higher lever of danger (so long as you be careful you won't die). I estimate a simile multistage coil gun would run about $200, assuming you make your own parts rather than buy pre-made ones. You could probably shoot a nail 100feet then. Coil guns are also totally silent.
A simple rail gun would run you close to $500. when a projectile is fired you will hear bangs and crackles of electricity, lots of sparks, and maybe even see plasma. rail gun projectiles shoot faster, harder, and have more energy. They are much more cool in general.
another totally useless science-y thing to build would be a Jacob's ladder. you need a NST (neon sign transformer), an appropriate current limiter, some bare copper wires, a plank of wood, and some electrical mains side wiring, power switch, socket.
what a jacob's ladder in operation looks like:
You can buy the NST on eBay for about $20. Home depot for the electrical mains side wiring, and a graphite rod with a ohm value of about 50. the graphite rod (at least 1/8th inch thick) is the circuit resistor, this will prevent the NST from using too much power and burning itself down. assemble the electrical mains supply wire and socket, put the graphite rod as resistor on the hot side of the wire, never put that on the neutral, that's a major electrical hazard if you do that. break the hot wire to the low voltage NST primary with a 120v switch. the neutral wire remains unbroken from the plug to the transformer.
depending on the NST output voltage, to figure out how far the two sides of wire need to be apart when starting the jacob's ladder arc use20kV per inch. if the output is 12kV, then put the bottom ends no more than 1/2 inch apart. I'd use at least 30" of wire for maximum visual effect. taper them outwards slightly to about 5" apart at he very top. use the wood plank to screw the bottom wires too as well a insulation. never place the wood directly over the NST, while it may seem a good spot to hide the ugly NST box, if you have less than 3" of wood the electricity can arc thru the wood and screw up your 120v neutral line! You may also receive a electrical shock if you have less than 3" of wood.
the NST can be also used for other pointless electrical fun at night, see electricity melt tungsten! corona arc thru a bottle! and other pointless things you can try setting up.
· 1 decade ago