Dry/Cure Cabinet - DIY Open-Source Precision Dry Chamber

I hope this is the right forum for this. I wanted to share my project and it’s progress with the community. This first post contains the bulk of what I’m putting together, I’ll be adding posts as I build and test this excessively-thought-out apparatus.

Background: I’m in a very dry climate, SW US. It’s typically 10-30% RH. Last season was my first real grow, and I dried in my shed in folded paper bags. Let’s just say…it didn’t do too well. It was dry within a few days and smelled of hay ever since. I tried putting some in jars early and burping, but it was too late. I want to see how close to ideal I can get (thanks engineering) with a little creativity and spare weekend time. I feel this is worth some considerable mental effort due to the role drying plays in the quality of finished product, this is probably the single most impactful process from seed-smoke.

The Concept: 50-60ish temperature insulated cabinet that exhausts when humidity reaches 60ish percent. This will be adjustable, and I could even make this ramp down over the dry cycle. Want to be able to hold a few pounds of wet bud. I’m going to publish everything (plans, schematics, PCBs, firmware) so others can build it if they want.

The Constraints: Cheap as reasonably possible, simple execution, fairly high capacity. I can’t dry in the house - space/smell/patience constraints, a tent like people use would be pushing the limits with my other half. I want to keep the unit in my shed. That means some crude thermal management.

How: I initially was thinking something like the commercial Cannatrol, and before I knew about that I had thought about using a broken fridge to house this “machine.” I’m not about to spend $1600+ dollars on this for a limited capacity like this Cannatrol Cool Cure , but it definately gives some good ballparks I can use to estimate my own capacity.

Let’s Sort Out Some Parts:
Dry Trays: I started by looking for drying trays. The kind for baking are really cool, perforated aluminum, but $10-20 each. Aggressive brain scratching landed me on mesh bottom propagation trays (25 for $40, basically $2 each). Perfect. https://growgreenmi.com/10x20-mesh-tray? (those aren’t the exact ones I bought but close enough)

Temperature: I ran some numbers and it looks like with my Oct/Nov temperature swings, I can keep a nice temp of 50-60F (80F high, 30F low late Nov, the plot is a little low on the hot end) if I use a large water cooler pumping water through a radiator in the cabinet. I ran these numbers assuming I would build it with 2" housing insulation board. https://www.homedepot.com/p/R-Tech-2-in-x-4-ft-x-8-ft-R-7-7-Rigid-Foam-Insulation-310891/202532856 I won’t need ice or anything, the cooler will insulate the water and I’ll wind up in equilibrium around the average temperature (60ish). Fantastic. I’ll need a radiator and a cheap pond pump to execute this plan, and if my long-season sativa makes it all the way to end-of-Nov, I may need to add a small heater to keep me running through December.

Found a radiator on amazon of similar size as my trays (20" nominal width) Amazon.com for about $20. Picked up a few PC case fans with PWM control for another $10 Amazon.com Scrounged a high-capacity fan and carbon scrubber from work for $0. Great, it’s all coming together then! I see the prices have “inflated” since I purchased both of these items :frowning:

If it isn’t clear already, in order to regulate the temperature, I need to maintain some small airflow over the radiator in the cabinet. I also want to circulate the air slightly to encourage drying, without blow-drying it. I need circulation to get a decent high-accuracy humidity measurement, and I’d like to filter the air so I don’t dirty my buds. I’ll make the circulation fans adjustable speed so I can run them quick after I budwash, and slow them down once they are dry to the touch. I’ll design to accomodate a 10" x 20" furnace filter, and probably cobble together an air inlet filter from another one. Perhaps something like this (but I don’t need a 6-pack) Amazon.com

How am I going to keep the humid air in and the dry air out? Looking around the isles of Home Depot, I found dryer draft stoppers for $8. https://www.homedepot.com/p/Everbilt-4-in-Inline-Vent-Draft-Blocker-BD04HD/205046954 These close unless there is positive airflow, so I can use on on the inlet/outlet of my drying cabinet to maintain humidity unless I’m actively venting it. I think with the output/input filter boxes also attached, I’m not going to be losing much through these. They feel suprisingly decent in-isle examination. It’s also a convenient way to attach my carbon scrubber to the outlet, so my neighbors don’t smell the dankness from my shed for 2 months continuously.

Control Electronics: My favorite. A couple weeks ago, I designed the controller. I made this DIY-friendly, so large SMT parts and inexpensive hardware. It uses an Arduino Nano Every ($10), which is about the cheapest Arduino that exists. There’s also the potential to drop in a WiFi or BT-capable Ardunio. It has 4 output channels for 12VDC, or 120VAC switching. Those are for: Humdifier, Dehumidifier, Cooler, Heater. I’m thinking ahead if anyone wants to use this somewhere they will need those, I’m optimistic I’ll get away with just my exhaust fan. The 12V heat/cool outputs can be PWM’d so you (or I) can make a proportional heater/cooler if you want. Naturally, I’m thinking of using a 12V pond pump to run my coolant circulation pump and large power resistors if I need a heater, so I’d use the PWM outputs to set the flow/heat power levels. FWIW this would also work great without modification for a greenhouse controller, or tent controller.

There are two 12VDC fan output channels with PWM control. The exhuast fan runs for a programmable number of seconds and whatever speed you dial in when the humidity exceeds a certain level. I did some math based on the humidity sensor response time, volume of the chamber, my fan, my typical humidity levels, and it looks like 5s on, and 60s wait to act again. I’ll set the speed of the fan based on the ambient humidity on average, but it’ll be about 25% speed (this will drop my 60% RH to about 55% RH). It will only run the fan if it crosses whatever setpoint I enter.

hum calcs

If you are about to ask how I’m going to sense humidity, I’ve got ports for pre-made sensors. I picked these Gravity: SHT31-F Digital Temperature and Humidity Sensor - DFRobot They respond fairly quick but it’s going to be important to burst the fan, and wait about a minute for the humidity to stabilize before deciding another action.

I finally got the boards in from JLC PCB ($4 each) and put one together. I wrote the basic program and you can set where everything turns on or turns off, and save it to EEPROM. The fan speed adjustments work beautifully with my fans. Now I need to build the cabinet. I’m drafting it up in Fusion 360 before I buy the foam and get to cuttin!

Of course, I have spreadsheets for the calculations (thermal/humidity). Some may be interested in that, but my expectation is that won’t be hugely popular. I’d be happy to show my work if anyone wants to see it, this write-up is meant to be inviting, informal and not overly technical. That’s all I do most of the time, so I think this will do a good job of drying herb without a comprehensive understanding of all the details. I hope some of this is useful to others, I’m learning a lot here in other areas.

Please let me know what you think! And I have some extra boards if anyone wants to build one :sunglasses:


Great idea bromigo…but thats way to much $$$, work and overthinking for me, I’m old school…I chop, hang dry and put in jars…I refuse to be a slave to this weed and try not to do any overthinking when it comes to growing/curing…


Totally get it! Here in the desert if I hung dry they’d be crispy in a day. Paper bags didn’t do it for me either. Nice stash BTW!

I usually enjoy the creation of a solution more than the resultant product. This is a fun diversion from the problems I usually solve, and I’m looking forward to the end of the outdoor season when I can try it.


If you hang dry for 1 day and put in jars it should rehydrate…I had a buddy who lived in the same environment as you do and that’s what he did…and if it’s still dry just put a pot leaf in your jar to rehydrate…I seen a lot of people take on big projects and cost them tall cash just to use it 2-3 times and scrapped the idea because it an extra step/work and $$$…



What a system !!! wish I had the brains to do something like this !!! please keep us posted on your “drying machine” --Thanks


a little bit like growing itself. for me, growing plants is at least as much fun as enjoying the finished product.

dry/cure is soooo important, and definitely tricky in those super-arid environments.

@FieldEffect extremely cool project, I hope you keep sharing your skills with us, OG is lucky to have you around :nerd_face: :sunglasses: :+1:


My eyes glazed over at the charts. Saved by the jars of buds


LOL, well, it’s certainly a mixed reception. I get that most people don’t go to this trouble, and that’s alright. That’s the fun part. I want to make this and I’m making it. I intend to continue posting it, maybe it’s helpful to someone.

I tried conventional drying methods last season and was dissappointed with the results. I definately hear the comment that this may not be worth it. I may continue the dissappointment this season, but I won’t know until I give it a try. In any case, I’m having fun with the project design and build.

Thanks for the feedback!


Correct if im wrong, but you had a lot of fun doing this right? it does seem overcomplicated, but you know your needs and most of the time when people go these lengths, its because its right up their alley.

When are you going to actually put this to work? me wanna see results :slight_smile: (specially because drying/curing has been a weak aspect of my game)


I’m finishing the mechanical design in CAD and intend to build it in the next few weeks. Building the foam box is really all that’s left to do. I’ve got some autos that started flowering a week ago, so I’ll have some buds mid-summer to test. And some photos come harvest season, that’s when it’ll really get a workout.

Absolutely I enjoy this stuff. I’m an engineer, I keep a roof over my head overthinking problems and generating decent solutions.


I like your solution but it does seem a bit overengineered. I grew up in the High Desert, 120 miles east of Bakersfield California. I hung my plants in paper bags but then put the bags in a plastic totes. By hang in bags I mean that I would get paper trash bags and add coat hanger over the top so I can hang a plant on the coat hanger hanging into the bag so its not touching the edges. then I put multiple trash bags in a Rubbermaid tote and put the lid on it. Then keep it in the coolest area you can find and open it a few times a day until the smaller stems crack and then just open it once a day until it is ready to jar. Best of luck with your experiment!


Sometimes the humidity is very low here so my solution is to rig the bathroom with no exhaust and an inkbird and a humidifier. The buds themselves add so much humidity to the air that the humidifier doesn’t even kick on until 2 days later. If it gets too high in those first two days I just leave the door open a bit.

Works well.

I appreciate the neatness of your design.


Have a look at this

Was going to build one


I like it! It’s very similar to what I’m building, I’m just using my low humidity rather than a dehumidifier. The control board does the same thing as the two inkbird H/T controllers.

I want a meat-curing chamber too…dry-aged beef at home would be incredible


First setup was a wardrobe box with a small 120 mm PC fan on an inkbird set at 60% RH. That worked well, and extended my drying time from three days closer to seven day.

Now I just dry in the flower room with the environmental controller set to 60°F, 60% RH.

Keeping the buds on the stem with as much leaf material as possible is also a huge help.


I currently use a drying box on the same basic theory, and it works pretty great for me


I’m just over-doing a box at the end of the day, and designed an open-source controller that is more versatile than the box.

It’ll fit 19 trays, so it should accomodate my ambitions moving forward. Quick guesstimation time: the Cannatrol is about 20" tall inside, and looks to have square trays 15" x 15". 6 trays about 3" apart (similar to my tray spacing). The trays are slightly larger in area than mine (active area of mine are about 200sqin, and I’m guessing the Cannatrol is about 225sqin), and they have a stated capacity of 2.2 wet. So I should be fairly safe in jamming up to 6lbs or so of wet bud in here. Again making broad strokes with my assumptions, this is probably 1-2lbs of dry bud after drying is complete.

I’m growing strains with supposedly staggered harvest times outdoors. Starting end of September, I’m hopefully going to have new harvests coming in for dry about weekly, and as things dry I can consolidate that strain to fewer trays.

2 sheets of 2" R-TECH sheeted foam. Now I just need to figure out how to drive home with these sheets in my car (small SUV). 4’x8’ sheets are going to be impossible to accomodate unless I do some cutting in the parking lot.

I yelled at my computer for longer than I’m willing to admit trying to figure out how to reasonably render the trays, Fusion 360 seems about as backwards and counter-intuitive as they could design it. But I’m not a mechanical guy, so maybe I just don’t know enough about drafting to be functional in it. Just getting the box looking like I wanted was a chore enough.


Wind down the windows in car
Strap 8x4 sheets to top of roof ( strap going inside window thru car and over sheets and back in again a few times )
Secure strap
Climb in car thru boot to drive of

If straps are thin , instead of going thru windows , open doors secure sheets to roof then bounce in and close doors ( thin straps won’t affect rubber seal on doors when closed )

Ha ha I used to work in builders yard , you be surprised at what people attemp to put in cars lol


And drive slow ish : )


How are you pinning boards togeather to make box ?

Pencils or pens drivin in like pins ( dowels ) and some silicon

Or aluminium tape , it’s good and strong and won’t come undone over time like duct tape does