Properly built wood cabinet is as good a deterrent as a cheap steel one. The main reason you want wood is to let pressure escape. Don't want 30-40 lbs of powder in a closed container made of metal in a fire, and static building up on it either. You can line the shelves with non-spark, non-static liners though. As far as i remember, the specifications for the cabinet were removed in 2013, at least, I couldn't spot them at the time I looked for them, used to specify brass hardware. The markings are still in place though.
What is shown in here says painted shelves in a metal unit are adequate;
https://www.nrcan.gc.ca/explosives/a...rage-sale/9829