I bought a sand blaster from Supercheapauto for $20. I think you can also get them at Bunnings, The brand is "Airpower" and are a range of cheap air tools that seem to be excellent value for money for the hobby user. I also, for the same price per unit, bought a brad nailer, a gravity feed spray gun, a half inch inpact wrench and a high speed die grinder. It is styled like a spray gun with a range of different nozzles for different jobs and only holds about half a kilo of sand at at time but for small jobs it works perfectly well. I run it from a 1.5HP direct drive el-cheapo compressor. Just be sure to wear adequate facial protection, a surgical mask to stop breathing in fine silica and a full face shield works for me.
