Glad I bought as much as I could in-person; the remaining supplies for this project have been stuck in transit due to the holidays and weather. (I also ordered an orchid a couple weeks ago that has been in transit since Monday, waah! Remind me to never order anything in December again.)
While I waited, I built the inner structure with 1/2" welded hardware mesh:
With the leftover mesh, I replaced the bulky frame I'd cobbled together inside my warm-growing terrarium, freeing up some much needed space:
The first things to arrive (incidentally the last to ship) were
these Garland windowsill trays. They're a British product and the measurements online were all over the place, but fortunately they fit two-deep with the lip overlapping, which will be better for catching runoff than having them flush:
I put a layer of LECA at the bottom of each and cut the egg crate diffuser to size:
Is there a secret to cutting this stuff? I ended up with a million tiny pieces of plastic all over my living room, ugh.
Supplemental lighting should arrive tomorrow. I ordered a bunch of orchids from Andy's current sale, which thankfully won't be shipped until after the holidays.