Who here builds and fires off spud cannons/potato guns? Just built one myself and had a blast doing it then had really great time firing it off in my backyard. For safety sake I used a piece of wadded up printer paper and it worked like a charm being pretty harmless. Mines a bit big which concerned me when I first fired it since it's about 2 to 3 feet long for the combustion chamber. It's about 4ft 8" to 5ft tall with everything added on including the 3" diameter barrel.

I made one in high school. I somehow managed to avoid being arrested. Still not sure how I did that.

Haven't built any. I preferthe tennis ball mortar. Quicker to build too.

We built one! PVC pipe, BBQ igniter, accelerent and a spud. Felt like Fallout 3 schematics lol

I've always wanted to build one, just never had the know how and the supplies

It's quite easy really and pretty cheap, but always best to start out small. I didn't have the BBQ igniter so I resorted to the old school "Cannon" method of putting a flame near one opened end of it. To help reinforce the thing to prevent cracking I used ducktape tightly wrapped around several areas of it.

Sadly because there are jerks out there that misuse these things I was cautious and made sure to check with my local law enforcement. Called the Sheriff Office and the officer said he saw nothing in the books about it being a Destructive Device. He also asked someone else who was more knowledgeable about it and said that person told them they were fine. Only thing I needed to do was operate it in a safe manner and that was about it.

Parts wise I got everything I needed at Home Depot and it cost me around $35 to $50 not 100% sure.

Here's what I used myself:

1x 4 Inch Diameter Pipe about 2 feet long possibly 2feet 6" long
1x 4 Inch coupler
1x End Cap and Plug *used for sealing your combustion area*
1x 4 Inch to 3 inch conversion piece
1x 3 inch diameter pipe about 2 to 3 feet long *your barrel*
1x Pipe PVC cement
1x Pipe PVC cleaning fluid

Biggest thing to do is clean every area you are about to fit together then use a generous amount of the PVC cement from what i've seen. Also takes 24hrs to let that cement really harden so it is good and tight.