I like the original design, but I have no 17mm Inbus and I don't want to buy one. So I added some material to use a 1/2" ratchet directly. I used some force at the tank cap and it holds well.
The 01 file is the one I printed. But because of the first original STL which was mirrored, so is this. To print it, use mirroring in the slicer.
The 02 file can be printed directly and should work fine, but I didn't test it.
I'm not sure about the strength of the PLA, so I used 100% infill. I think 20% infill with 6mm outer shell would also work, but I didn't test it.