I think A_R_B's fixed torque wrench is one of the best things on Thingiverse. I've got a couple and needed another and thought that it would be nice to not have to dig out a socket when I was working with them. Pretty simple design, could possibly work with other 19mm bolts but not designed for that - this is really designed to work with those fixed torque wrenches, which is why it's listed as a remix.
Use is simple, should fit well and do what it needs to do. Handle is short but is plenty for the torque that should be required on the end cap if your printer has done a good job on the cap and the case.
Fusion 360 original file included if you want to change anything. If you do, please post a remix!
No need for a fine layer height, there's nothing really precise here. Up the shell count to 4 and you can keep the infill really low and still wind up with a good strong print. 4 shells and 20% grid infill in Cura gave me a perfectly usable wrench which worked even when my threads were a bit messy and tightening the cap was really hard.