Found this nice Porta Blast and although it shows some wear and light surface rust, it looks as though it wood still work. The handle squeezes freely but needs pulled back up by hand. (May just need oiled -- I'm leaving as is.) Port a Blast is printed on one side of the handle and Lindberg Products Co., Camino, Calif Pat. Pend. is printed on the opposite side.
Port-a-Blast Porta Blast Sandblaster Abrasives Sprayer Gun is the name I found on the internet other than this one. It is a newer version, I believe. This one I think could be fairly old as the patent is pending.
The top unscrews easily and the inside appears to be in good shape; the spout also unscrews with ease. Although there is rust and the paint is chippy on half of the outer body, it is still in good condition for its age. I'm told this dates to the 1970s or 60's or so but it is not dated and I could not find a similar one to compare it with. I think it might be older.
This Porta Blaster measures approximately 10" x 7" x 4-1/2".