Holds 22 AA batteries. Honestly, there are probably cooler AA battery holders on here, but I made this one for myself to fit in with my other rechargeable battery holders. I started using these for some camera batteries and found that I really liked being able to see what's charged and what's dead by the orientation (electrical contacts in for charged, out for dead). So yeah...odd disclosure aside... :)
I like to size mine so that the batteries have a slightly snug fit, preferably just enough to be able to hold them upside down without falling out. But you can use the 'x1' part file to iterate and get the fit you like by scaling in your slicer of choice.
I printed mine in PETG with an 0.8 nozzle on 0.64 layers.
If you want some additional info, and/or to check out the other variations, you can find it here.
Or if you want to brave my ugly CAD, the files are available on OnShape here.