The mount is 250 mm long so you have to turn it probably. Print in standing position with support.
Here is a screencast about the design process: https://youtu.be/gL1S5TXXMjc
Update #20170223 #1: I made another version which using lock clips to mount the holder to the bottom of the backpack.
Update #20170223 #2: I also made a clip lock version for the 5.11 Rush 24 backpacks.
Technical
To assemble the mount you will need:
- some velcro for the bottle locking parts
- some 25 mm wide strap to attach the mount to the bottom straps of the backpack.