His last time on was 10/14, that does seem like too long, you should try to email him if you haven't already, his email address is listed on his site here: The Lightning Stalker
Gave it a try, hoping to see something back. He's not the only one MIA here over the last few months, RHD doesn't post much lately, but I do see an occasional one sneak in every now and then from him. This appears to be the natural order of LPF, people come and go, sometimes come back, but only a few constants.
Once, many years ago, decades ago, I filled a large weather balloon with gas from my oven, inserted a long cherry bomb fuse and let it go outside. While watching it rise higher and higher a neighbor came outside and lookup up at what I was staring at, it then exploded in a ball of fire and she said "OMG, those poor people". She thought it was a hot air balloon that blew up. I had tears in eye eyes trying to suppress my laughter so she wouldn't know what I did... I thought I might get into trouble for it, I suppose I could have.
I've made the same style pvc potato gun. I did not use propane and an ignition coil. I just used a can of aerosol spray paint and a bbq lighter. It was quite a bit of fun, no where near as loud though. It sounded more like the typical Smoke Canister and Tear Gas canister launchers. "Thooomp"