If you want it to be plausible, then you are somewhat limited to natural resource-based operations such as mineral extraction or an isolated government operation such as a missile test site.
The Southern Pacific's narrow-gauge Keeler Branch is a good example of the former (loading soapstone, sodium carbonate, and talc at Keeler until the end), while the Santa Fe's Boron Rocket Spur is an example of the latter.
Note that one can represent a large industry in a small space simply by placing a flat against the backdrop or having a track or two disappear behind a low hill (perhaps through a gate to a government facility).
More information from you on the era, size, and arrangement of your layout might help others help you with more specific suggestions.
The mid-sized HOn3 layout below is based on the Keeler Branch and has a number of mineral-processing shippers -- but of course it wouldn’t have to be narrow-gauge.
Layout Design GalleryLayout Design Special Interest Group
How about a glass factory?
The amount of minerals that can be mined in the desert is long. You could have a choice of various mines from small to very large. Green house industries is another one. Bottled water from deep underground springs. The list is long.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
I'm building a desert Shortline that interchanges with a class 1 RR.
Besides "Cement Plants", (too big), what other industries would be found isolated in the desert, with a very small town nearby, (i.e. "VERY SMALL")? This is not the thriving desert community with a big operation. I'm talking more wide open desert spaces type scenario.
Anyone know?
Thanks
BBF