12" cube terrarium with Hygrolon background
 

I went a different direction than I originally planned, mostly because I remembered I had some Hygrolon left over from a prior project. It's a really cool substance.

I'm going for that natural 'stacked' look where there are large plants with small plants growing on and around them, and I think it's working OK so far. Hopefully that continues when the plants fill in.

The background is made of granite and cork bark for structure, covered in Hygrolon, and the Hygrolon is mostly covered in moss and liverworts. No glue or sealant, just carefully braced rocks, holding things in place with weight, and Hygrolon tucked in and around the edges to secure it. There's a few stainless steel pins in there, to secure the edges and to hold the plants in place until they root, and I'll try to remove those once everything is established. If the pins don't come out, oh well, that won't hurt anything.
I put a couple of gaps in the Hygrolon to expose some rockwork, and there's a hunk of lava rock kinda high on the right side that's exposed. That top area still needs some cover, but the ferns should spread over it.
Stays nice and humid inside. There's a layer of acrylic over most of the lid, and a computer fan with a humidity-keeping plastic shield circulating the air. So far, nothing seems to stay outright wet for too long, but the humidity feels pretty high and nothing looks dehydrated.

The terrarium gets misted heavily at least once a day, and I keep about an inch of water in the bottom to keep the Hygrolon wet. All of the wall stays at least slightly moist all day, and the bottom stays fairly wet.

If you notice any orchids in a spot that they might not like, feel free to let me know, I'm still learning.

https://i.imgur.com/aflHBS7.jpg
Everything in here qualifies as a miniature, I think, except maybe the two larger Bulbos and possibly the Phal. I know the Phal will get on the larger side, but I saw some adult plants, and I think it should be fine in that spot as long as I angle it right.

https://i.imgur.com/zoXruhu.jpg
The center plant is a Phalaenopsis equestris. The roots are a bit shriveled, but the growth tips are still green, so I think it's adjusting rather than outright dehydrated. Its roots are wonky because it was a keiki cut off a flower stalk and had never been potted.
The little vines underneath are an unknown peperomia, and the tiny orchid to the bottom right is Bulbophyllum alagense "large form".
The vine creeping out of the Bulbophyllum clump is a baby Rhaphidophora cryptantha, which is a shingling vine that'll look great once it latches on and grows. I hope to make it work a bit like a focal point, wandering around the background and taking the eye with it.
The orchid in the very back, behind the deer skull, is a Bulbophyllum breviscapum. I'm gonna try and get it to fill in that back area.

https://i.imgur.com/nCZ4r8y.jpg
The center orchid is my favorite in here, a Lepanthes gargoyla. It blooms tiny scarlet flowers along the center of its leaves. Not blooming currently, but I think it has some buds? Not certain, they're very tiny. I'm hoping it splays everywhere when it gets bigger.
The orchid in the very back, with the narrow leaves, is a leptotes of some sort. Bicolor, I think, but the tag is missing. I'll find out when it flowers, I suppose.

https://i.imgur.com/RwsgQtS.jpg
Most of the greenery here is liverwort and moss. The patch of narrow leaves in the bottom center is a mini fern.
Just above that, the tiny orchid below the large one, is a Bulbophyllum catenulatum, and then the larger Bulbo above that is a B. colletti.
The wide-leafed orchid behind that is an Aerangis fastuosa, tucked under another mini fern because it doesn't like bright light. The orchid in the center of the pic, splayed over the lava rock, is an Agraecum didieri. I like its wonky spray-foam roots, and I want to see what it looks like with those roots around the rock. I'm misting it to keep it wet until it fastens on.

https://i.imgur.com/NcmXfMn.jpg
Close-up of an Angraecum distichum. That's a cutting, it'll grow into a big clump.

It looks great! :goodjob

Indeed, looking good.

Minor update.

https://i.imgur.com/V9ljLLXh.jpg
https://i.imgur.com/3PJ6OY5h.jpg
https://i.imgur.com/MiZiQs2h.jpg
Blooms and a keiki! The Angraecum didn't like its original spot, it was getting light-burnt, so I moved it much further down and it's been blooming. And it smells good, to boot, though only if I stick my face in the terrarium.
And my favorite orchid so far, the Lepanthes, is making another baby of itself. Awesome.

Very nice! Love A. Distichum, mine is growing well, they have such amazing leaves.

How big overall would you say is the Phal equestris? Wondering if it should join my collection of mini phals, but worried it's a tad too big.

What a beautiful terrarium/orchidarium, well done! I love your choice of plants, the end result is very pleasing to look at.

Phal equestris is tiny, as far as Phals go. Most of the equestris types I've had are very small, with leaves about 8-10cm long I'd say. The exception is the var semi-alba, I've had 2 of them, and both were rather large by equestris standards (15-20cm long leaves). The plants do take up space when they decide to produce keikis, which is very frequent.

Ah, okay, that's probably miniature/small, rather than an actual miniature.

Miniatures typically refers to plants where the entire plant is less than 15cm (without inflorescence). Phal Gibbosa or Appendiculata are around 5-8cm for the entire plant. :)

Might squeeze an equestris in though, if I've got the space, as it looks very nice, particularly the alba version. :)

That's true that it's not a true miniature, it just seems like one when you compare it to the Phal genus as a whole! I used to have a Phal parishii and lobbii (back when I tried growing mounted plants) and when I do a mental comparison, equestris is a bit of a giant compared to them!

Is size a concern because it needs to fit in a terrarium?

Not particularly, it's more about just loving the real miniatures....

The adult Equestris at the greenhouse were about 6" across. They're on the small side, but I don't think they count as true minis. Mine is smaller than that, it's a baby, but it'll about fill up that corner of the terrarium when it gets bigger. That's on purpose, I wanted a comparatively large plant to tuck some small things under.

A. Distichum smells great, and this is just a little one. The one at the greenhouse was a big bundle of probably 12+ stems the size of mine, this is just a cutting. I wish I'd seen the big one in full bloom, this little bit had 3 flowers and I'd imagine a cluster that big would have a ton of flowers.