Those are defiantly some really nice lithops! And I love the ping setup too!
I also have had such thoughts, this seems to be the most close to the native land, but I may be mixed with some moss inside increase water retention.
Also, I have a suggestion to help with your pings growth. I haven't kept any (yet), but I know that tufa rock will wick up water. If you place a tufa rock in a bowl of water, the whole rock will be moist to the touch. It won't be so wet as to have pools in the rock's pores however, but it will be enough to leave moisture on your fingers. It looks as though you have several tufa rocks stacked on each other, this will stop the capillary action, thus, the top rocks will be dry.
I suggest sitting one rock in a bowl or dish of water. This may help keep your pings hydrated.
Incredible! I really hope this works out for ya I would like to do something like this for our native P. vulgaris...
There's a population of P.vulgaris just outside the town I live in (Ithaca, NY). They grow down in one of the gorges on vertical rock faces, so P. vulgaris (and other cold-temperate pings) would probably do well with this sort of setup as long as you keep them wet.
Wondering, if this is still working out for you?
Looks like you are good at growing Mexican/equatorial Pinguicula. Thanks for sharing your efforts with us.
I'd often daydreamed of doing something like this, too. But, when I was actively growing, I just couldn't spare the space. The closest I came, was making some hypertufa (artificial tufa rock made with cement mixed with perlite, gypsum and pumice). I used a 3.5" plastic pot, as a form, and made it with a planting hole in the top-center. After forming it, I removed it from the plastic pot and planted a Pinguicula gigantea in it, keeping it in a tray of water. It worked well enough, but certainly didn't imitate a natural environment as well as your setup does.
Did you find the T5 fixtures in the pet/aquarium section of Walmart?
Tucson, Arizona, U S A