We keep a small-box media blast unit in the shop to clean up small parts and such, and we’ve found it extremely useful — so useful, in fact, that we’ve considered picking up a larger open-air unit to use outside. It’s a pretty big investment, though, and the large ones take quite a bit of time to set up (and clean up).
Something like this might be a good interim fix: It’s a small hand-held unit that gravity feeds from a top reservoir and plugs right into your standard air compressor line.
It’s not going to help you tackle truly large projects, but it would help you blast small areas of a piece that’s otherwise too large to fit into a smaller box-type unit. We find ourselves in that kind of situation pretty regularly, so we’re thinking about trying it out.
The top-mounted hopper holds 9 oz of abrasive, and it comes with a single round nozzle. Astro Pneumatic, it’s maker, recommends a 90 psi working pressure. Though they don’t mention airflow, you’ve gotta figure it’s going to require a good bit. I wouldn’t bet on using this with a little pancake compressor, but if you’ve got a 5 gallon or better you should be OK for use in short spurts.
You can find this unit all over the web for $20 or so.