This is a water bottle holder designed to be zip-tied to a bicycle that doesn't have bottle cage screws (or for where you want to attach it to a tube without screws).
I recommend ABS.
It prints in three parts which need to be glued together. (It is not essential that the bond be super-strong.) I used ABS juice.
I also cut out a bit of inner tube and hot-glued it on the base of the strap piece to keep things even more stably attached to the bike.
No supports needed.
The dimensions are fully customable. I designed this for our local store brand disposable water bottles (which I refill a lot of times, and which nicely fit in my pants pocket). You want the lower holder to fit snugly, and the upper holder to be smaller than the upper diameter of the bottle (the cinch parameter controls how much smaller). Because the upper holder expands to take in the bottle, you want it to be thicker plastic.