I posted my rig a while back that I think works in a similar way, except it uses a bag instead of a box. I can't control temperature yet, but when RH gets above the set number, a little fan comes on to bring in drier outside air, and an exhaust valve opens to let out the air that's too humid. I've been using it for a year or 2 to slow down the drying and prevent over-drying. I can't wait to see your final specs.
Any container that is more or less airtight can do the job, the specifics mostly relate to how much weed you want to be able to process at a time, and what shape your weed is in (trimmed, or not) when put in the dryer. I find that now that I have the drying process sorted, I prefer to do a final wet trim down to finished bud, so screen trays were the way I organized the drying bud in my current dryer.
I tried drying partly trimmed branches hanging in a cardboard appliance box last year, but it was too leaky to support easy RH control, and I didn't include a moisture source to keep the RH up when the bud got too dry to do the job on its own. I was not even thinking about doing the cure in there, just replacing the brown bag part of the mischief. Finding out that the cure works with just more days in the same dryer is what convinced me to go the whole project this year.
Temperature control is a lot less important than RH. Any more or less normal room temperature will almost certainly produce the same end result, namely cannabis at a water activity of around .57, which seems to be perfect. Bottom line is that bud that has reached equilibrium water content in 57% RH air will be .57 water activity, and shelf stable. As long as the RH is at 57%, the bud will dry perfectly whatever the approximate temperature. The main variable in response to small differences from 68F is the lower temperature, the slower the dry. The bud will still end up at .57. This likely warrants some experimentation, it is possible that doing the dry/cure process at lower temperatures might nudge up the quality of the bud by slowing down the dry. The recommended 68F@57%RH does an excellent job, but that may be as much designed to get quality commercial bud on the shelf as quickly as possible, not to get the nicest bud possible when a longer process is not minded. The advantage of this sort of dryer setup is that the user can design whatever drying sequence is needed to adjust the results, all under precise control. It would be dead easy to extend the dry either by doing it at a lower temperature, or doing it in stages which start higher than 57%.
All food for thought. With appropriate lubrication.
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