Advice for a budget mini (12x12x15) terrarium setup?
 

Recently I have been looking to improve the growing conditions for my orchids, all of which are grown indoors, and it seems that a good way to do that might be to invest in a terrarium setup. Also, I'll be moving soon, and will have to move back and forth several more times over the next few years, so it will be helpful to have some of my orchids in a more contained and controlled environment. This would be my first time trying to set up anything like this, and I am trying to do so as affordably as possible.

So far I have mainly been referencing this "DIY Orchidarium" guide and this "Building an Orchidarium" guide. I am not planting the bottom/surfaces so my end result should look more like that in the first guide. For the terrarium itself, I am probably going to go with a 12x12x15" size from Zilla (it seems ExoTerra is the preferred brand but the 12x12x18 is a little to big, and I the 12x12x12 seems too small).

The orchids I plan on starting out with in this terrarium are Asc. garayi, Aerangis hariotiana, D. loddigessi, Bc. green bird, and Sophronitis cernua.

Lighting - I currently have 2 of these cheap grow lights from Amazon. I know the quality probably isn't the best but if I can get by with these I'd rather not get new ones. I'm not entirely sure how best to mount them to the top but one idea I've had is just to get a vertical table extender and clip them onto that. Ideally, I would set one to the high light setting and one to the lowest light setting so that I can provide lower light levels for orchids that need it. However, with the space being so small, I don't know if this would actually do anything. Another idea would be to place shade cloth over half of the lid, but I'm not sure which density would work best for this situation.

Humidity - Since the space is relatively small, I was thinking I might be able to get by with one of these controlled foggers. I will also use a ThermoPro for monitoring. Since the space is small, another option may be just to mist manually, but I don't know how effective this would be. Living in an air-conditioned space, my RH is on the low side (low 30s-50%), and I'd like to get the humidity in the terrarium to at least 70%.

Airflow - The second guide uses a 2-fan system. Since the space is small, I won't need both going at once, though I'm unsure if my primary fan should be top-mounted or inside the tank.

Drainage - I like the idea of making a false bottom with egg carton as described in the second guide, but I'm not sure whether or not I should add anything else for drainage (leca, tubing, etc.), or if this space is small enough for me to just let evaporation do its thing. I'm not too sure how the drainage works in that guide but it looks like just a manual siphoning thing.

Watering - Assuming electrical hazard is not an issue (which I'm not sure of), would it be appropriate to water directly in the terrarium? I water with one of these, which is more like a heavy-duty mister, so the plants wouldn't be getting drenched.

Day/night temperature differential - This gets tricky because I don't think the terrarium I chose can fit a heating pad underneath like the ExoTerra models. Running the fan at night could provide a lower temperature but it would probably decrease the humidity too much. It's possible that the lights may provide enough heat during the day to make a difference but I will have to wait and see about that. Currently, the AC in my house is set to 76F during the day and 74F at night, and I live in zone 9, so it can get quite hot outside.

Other considerations - I like the idea of using an anti-mold painted pegboard to hang plants, so I will probably do that. For the lid, I might see if the mesh lid the terrarium comes with can hold humidity and use that if it works. But I will probably have to buy a sheet of acrylic. The second guide mentions having one custom made but I am hoping I can DIY any cutouts I need.

Thank you for reading if you made it this far, I know this got a bit lengthy. Please feel free to point out anything I missed, and any advice would be greatly appreciated.

Bump

I don't have terrariums right now. That's a good start. Don't worry too much about day/night temperature variation. Always be figuring out how to simplify things so you don't get sick of it.

I would think the plants + damp medium would be enough to keep the humidity high inside a case that small. Toss a damp towel in the corner and the humidity will probably be too high. Lol

I've used some old plexiglass display boxes as mini-orchidariums in my office. I put the box on a heating mat and put a couple of computer fans inside, and some cheap grow lights. I usually water by taking the plants out and running them under the faucet, but sometimes I just spray them in place. If the plants are well-watered, the humidity stays high. I usually grow phalaenopsis in them which I water daily or every other day during the week and not at all on the weekends, and I've had mounted plants in them and they have done fine with daily watering.