I used the solenoid valve from a Glade air freshener to control the disbursement of butane . I used a 300kV boost coil to generate a continuous spark. A single button triggers the release of butane through the solenoid and the spark. I mounted the entire assembly to a leather wrist-guard.
This project is awesome but you really need a flashback arrestor to make this 100% "safe" to use. I don't think the risk is high considering the flowrate but in any event it'll save your arm if an errant flame manages to get back up the line.
I know this is from years ago but this air freshener no longer exists. Almost all are motor-controlled.