Of all the ways to strip unwanted paint and rust from project surfaces, few are more popular or less complicated than media (sand, walnut shell, baking soda, plastic, hematite) blasting. Chemical stripping or sanding may cost less initially, but the expense in labour and time for either of these can be high and the hospital bills for paint-stripper induced chemical burns, eye damage and lung/skin cancer are sure to add up. It's no wonder that media-blasting is the tool of choice for serious "strippers." A DIY sand blast cabinet can be a helpful device.
Although a blasting cabinet may seem to be little more than a box with two glove holes and a window, the truth is a bit more complicated. Among the box's basic components are:
1) The box, window and gloves 2) An air intake and exhaust system to reduce dust build-up 3) A reservoir to catch used blast media, a sieve to feed the catch reservoir, and a media feed reservoir. 4) The air compressor, lines, fittings, blasting gun and siphon tube. 5) A lighting system so you can see what you're doing.
Building the box
The media blasting cabinet itself can be any size you need it to be, but remember that you can only strip what you can reach. Consider cutting a pair of glove holes and window every 60 cm (24 inches) or so, and buy or build plugs to cover the unused holes. The cabinet can be made from any material; particle board, plywood and metal are all popular options. A good set of gloves can be bought for less than £22.
Whatever material you use for windows (glass, plexiglass, acrylic sheet, etc.), you're going to need to make it removable for servicing. The media that strips paint from your parts will do an equally efficient job of scuffing your windows, so coating them with polycarbonate film is highly recommended. Replacing scuffed polycarbonate film is a lot cheaper than replacing windows.
You're going to need an exhaust fan and an intake port to keep dust to a minimum. Place the intake port on one upper corner of the box, the exhaust on the other and put a filter or pillowcase on either end.
You'll need a two-stage reservoir; one underneath the cabinet to catch the used grit and another to feed the gun. One neat configuration is to use the bottom of the cabinet itself as your catch reservoir and install a downward-hinged trap door that dumps into the feed reservoir through a filter screen. You can use a double-layer of aluminium porch screen to catch debris, but more specialised and commercial grades of screen are fairly cheap and easily accessible.
Lighting options are practically unlimited, but consider installing a fluorescent bulb that runs the full width of the cabinet door and protect it with a polycarbonate tube. Full-length fluorescent tubes are fantastic for preventing shadows, which can hide imperfections and cost a lot of time in touch-up work.