FWIW - I got a wireless 4-channel fireworks controller for $18 from China:
http://www.ebay.com/itm/Fireworks-F...34AAOSwa~BYUqlN
Have not done much testing with it yet, although the range seems better than any I have used before. In large part since the ones I used before had no antenna on the transmitter, while this one does.
Need to add output wires with micro-clips. The receiver has 4 outputs, each one with an LED that lights up when "fired".
Technically, no removeable safety interlock key.
For this one I figure a good approach will be to wire up output #1 and #3 in series so that both buttons (1 and 3) have to be pressed for launch. Or to require two hands (without using a holder or table), #1 and #4 for one output set. In the past, I had one with a keychain remote where I pressed a red button to "arm" the system for 5 seconds, then pressed a blue button to fire... within that 5 seconds. I used it mainly for launching R/C Rocket Boosted Gliders by myself for practice flights. This one does not have that 5 second arming trick, so if I want to use it launching RBG's I'll use it with the outpits for #1 and#3 so I can press both with one finger.
I will note that for my personal launch controllers that DO have a safety key, the key is TIED to the control box so it does not get lost.
For the real tinkerer, then crack open the TX, gut it , remove the button leads, and wire up your own button, safety interlock key, and new LED since the old one may not be practical to use.
The receiver uses four AA Batteries. So,pretty much limited to Solar ignitors or low-current ignitors (it comes with a few e-matches, and the price of 100 e-matches are really cheap!). Not for copperheads, Firestars, or other higher current ignitors orclusters. If I wanted more amps, I'd install NiMH (or nicad) AA's that deliver more current over a short than Alkalines. If I wanted even more, I'd use a 7.4V (2S) LiPo with a 6V Voltage Regulator, as the 8 volts from a "7.4V" Lipo might fry the circuit. Or use it to trigger a relay.
A problem with the wireless systems, as well as relays, is no good way to check continuity. To solve that, I made up a continuity checker box for the pad, with a toggle switch to go from continuity mode (not armed), to armed mode (no continuity). Because there was no safe way that I found for doing it otherwise.