I would not build a pressure tank, I would buy one factory made. they can be dangerous because of the pressure it will have to withstand.
I had a
Skatblast Sandy Jet and it worked great, but wore out valves, hoses and nozzles. Also made a damm big mess.
Here is a link to a site for info.
http://www.smartshoppersinc.com/sand-blasters/sand-blasters.html
