Swivel Stands?

[NP Carling26]

I'm looking to purchase or construct a strong swivel stand for my pneumatic cannon. Currently I have an over/under design, with a 4" pressure chamber and 2" barrel. I would love to design a quick way to mount (and demount) it to a swivel stand (tripod, preferably) for easy aiming and firing. However, it's a bit heavy, I'd say pushing at least 25-30lbs, I'll have to get an exact measurement. So I need to build a durable, heavy duty, swivel stand, or find a decent one for cheap. Anybody ever done this before? What's your suggestion? Also, pictures are always appreciated.

[jackssmirkingrevenge]

http://www.ebay.com/itm/Brand-New-1919A ... 3f16b68696

Bit pricey though, but you get the idea if you want to make your own