[ARCHIVE ANSWER]

Why would you want a positive pressure system? It's going to push the smell out of the container. A better system would be
a sealed container under vacuum.You build a container out of milled alum, a cylinder would be nice. One end would have a removable cap, that would be vented. The other end would hold a vacuum and a respirator cartridge. it could
plug into your cig lighter outlet. The air would come in the front pass through the vac exhaust and out through the filter. I imagine a resp filter that can filter out toxic gas should be able to filter out the smell of cannabis. Just an idea I had, no
clue how well it would work.But 10 points to the first entrepreneur who develops a stash box with a positive pressure system, which is how a bio-hazard suit is designed. This filter system cleans air and forces it in to the suit, keeping all the
nasties out. It must match the chemicals/agents involved. These suits have a finite shelf-life, and are limited in exposure time before being disposed of. These suits are not really non-permeable as much as a temporary barrier with a definite point
where they are compromised.