Definitely check out Turntex.com and cactus juice, I have used it and its an awesome product and Curtis is a grade A business man.
He sells a nice rig for stabilization. You can also get a pressure pot from harbor freight to do casting in at around 40-60 psi, dont exceed the pots psi rating.
Nice thing about the pot is, you can buy a piece of lexan, I used 3/4" I would rather have overkill than experience a catastrophic failure.
Just bore 2 holes in it for a brass T to be threaded into and into that put a vacuum gauge and a ball valve for control of vacuum.
Into the other hole I put a quick connector for an air compressor, the male fitting. Then you need a vacuum pump, harbor freight sells them also ebay is a good source.
Visit Curtis' site turntex.com for listings of decent pumps to look for. run your hose from the pump and on the end add the female end for a air compressor quick connector.
I used these because i had plenty laying around. You can use whatever you like on the pump and in your piece of lexan, anything to connect them.
For a gasket I got some rubber shelf liner from lowes, its cheap and works great. Your ready to stabilize! Go to the above mentioned site and watch Curtis' video on his system,
follow the instructions on his vid with this rig. That all said, just buy the one Curtis offers, its easier, in the end costs about the same and is a nice product.
I bought one! I use my pressure pot to cast in and if i need to stabilize something larger than my cactus juice rig will hold I use my pressure pot and homemade top.
Hope this helps some!
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Steve