This is a T-Deck enclosure. It is essentially AlleyCat's enclosure - PLUS an area for the amp, extra battery and charger.

By adding a bi-directional amp to your T-Deck or other LoRa mesh device, you can sometimes significantly extend the reach of your signal, both sending and receiving. I have had great success with the sunhans 1 watt amp, and other even higher powered LoRa amps found on e-bay.
As soon as someone showed me this LoRa amp on Ali Express, I knew I was going to give it a try as soon as I had time. These amps are also available via Amazon now. They are around $25-30 currently.
I included instructions for assembling the full device, in case you want to try it out. I'm currently just starting to test this, but wanted to make it available for everyone else at the same time.

So far based on a few tests, it seems to work very well with the Blackout Comms firmware I build and maintain (lots of PDFs attached, related to that).
Distance-wise, I'm getting > 10 miles between similar units (mostly unobstructed line of sight), but I have not had time to find the exact limit yet. Your experience/environment may be quite different. There's little RF noise in my area.
I'm getting > 24 hours of battery life, but haven't bothered to run it fully dead yet. My goal was only 24 hours, so that's as far as I checked.
I don't personally use the Meshtastic firmware, but obviously this enclosure can work with T-Deck so if the amp plays nicely with meshtastic, this enclosure may be a good option for that as well.
This is a very tight fit - you may want to consider a smaller battery than the 5000 mAh battery I chose. Definitely don't crush a battery trying to get it all in!
Update: I did some more detailed distance testing at 3 separate distances, and here are the results I got on that day:

The author remixed this model.
I added space and mounting capability for a 1 watt/5v bi-directional amplifier, as well as an independent LiPo battery, charge controller, and on/off switch for the amp.
The antenna has been moved to the back of the case, rather than the case front, so it can attach directly to the AirBuddy amp.