Been wanting to try this myself, but don't have the time. Give it a try, make a journal, and let us know! You may be the first. There may be commercial makers out there that fire their formicariums? But we don't know for sure since its not public knowledge.
My guess is it would make an excellent nest, much better than acrylic or 3D printed materials.
I haven't seen anything around, not even someplace like Etsy where that kind of artsy fartsy stuff would most likely be. So, I'm definitely going to make a journal! I'm headed back to the ceramics studio tomorrow night to work on this project more, and if my first couple of prototypes show promise, I may start making them at home.
I've been wondering about it because it seems like cleanliness is a big issue when keeping an ant colony long term. It seems like most formicariums are designed for visibility, and not really for long term use/cleanliness. Since high fired ceramic, esp with a glazed surface, is glass-like, it would be a lot easier to clean and maintain.
The shrinkage makes ceramics a poor candidate for any multi-component assembly requiring parts to fit together with precise tolerances, as are often necessary when keeping ants. Instead of making acrylic fit into a ceramic piece, consider inserting the ceramic piece against the side of a box of acrylic, polystyrene, glass, or similar material, as is shown here:
The reason low-fire is prefered is the absorbency is better suited for the wet/dry cycles of a subterranean ant life compared to non-absorbent materials, on which any moisture would simply condense into droplets. The plastic formicaries are not optimal in this regard, but they are relatively easy and inexpensive to produce, which makes them a top choice for commercial formicarium manufacturers.
Yeah - the clay product I'm using is anticipated to shrink 10-15% between construction and final firing. Since I am adding an acrylic viewing window, and machine screws to hold it on, I'm trying to account for that shrinkage. It is satisfying when the 3/4" tubing fits perfectly inside the 3D printed holes in an acrylic nest, but there are other disadvantages to acrylic, too. I often see people combining different formicarium parts/test tubes/etc with blue tack or other adhesives to create seals, so I would imagine that's how I'd make up for any imperfections in the final build...
The raw clay body of a high fire clay still retains some porosity, it's not totally vitrified, so it does still absorb and release some humidity if left unglazed. Raw clay body also retains a rough, stonelike texture, which can be further textured beyond just the natural texture of the clay. That would help break up the surface tension of any condensation that doesn't get absorbed directly into the clay body... Anywhere that it is glazed would have a glass-like texture.
I have seen this design before, it's pretty much the only ceramic formicarium I could find pictured online actually. However, it looks like the design is extremely bulky/chunky, a really inefficient use of the clay. As a result the glass tank actually becomes the primary container, as opposed to the clay making up a standalone formicarium of it's own. My current goal is to build a few small founding sized formicariums in a slab jar construction (similar to these) where the acrylic can be fitted inside is a viewing window. Take off the jar lid to view the ants, but put the lid back on to give the ants darkness and privacy. There would be test tube ports where test tubes could be mounted to feed/water, or tubing attached to lead to an outworld. I'm trying to make the chambers large enough that some substrate could be added, if desired, which would also help facilitate ant colony comfort.
I like Nurb's suggestion of starting a proper journal on it, so I'll probably post that up later today with some pictures of my initial designs. I'll take some pictures of my first project tomorrow, and add those as well. 
