Right now I only have plans for one of them up right now, I'll have both up when I get a chance.
Until then, here's the plans for the pneumatic spud gun.  Soon I'll have some up for my combustion tato' gun.

Here...

COMING SOON-    COMBUSTION SPUD SHOOTER HAS CHANGED, IT IS NOW A 10 FOOT STARCH DISPENSER.  LARGER COMBUSTION CHAMBER, LONGER BARREL, RELOCATED IGNITION.......OH YEAH.  PLANS UP SOON.

Please note, I take no responsibility for what you do with these things.  It is your responsibility to practice caution with them, and also to know if they are legal in your location.  A potato launcher is very dangerous, and under the wrong conditions, it can easily take an arm off

I'd rather be watching t.v.