The revamped PI chassis is really nice, but I have a few PI 1's that I needed to slot in there, so this is a 3-rod version of the chassis. This is only useful for mounting PI 1's. I placed the "missing" rod mount on the front bottom, not the top. This is because I also included 2 sleds to mount PI 1's to. These are adapted from another design, to allow the PI to mount front-facing like the rest of the PI's, but you need the 3 rod version of the rack in order to clear the RCA jack that protrudes. Additionally, it's cut down a little in the back to clear the power USB.
There are two carts included. The PI 1 Sled is for the newer rev B of the PI. This version has mounting holes for screws.
Turns out however, I also own an original PI. No mounting holes. A second sled is included that uses clips to mount the PI instead. In theory this would work on a PI 2+, but, why bother?
Finally, if you build the full rack, make sure to not place a fan behind the PI 1's. On a 1, the power extends out the back. The fan will interfere with the plug.
I built my rack by printing 3 of the 3-rod carriers, and then the rest in the standard 4-rod version. 3 just happens to be the width of 1 fan, so I used 4 fans instead of 5. (Also, I have 3 PI 1's.)