This is a wrench for a very common oil filter of many oil heatings. Normaly you can open and close it without a wrench. But sometimes it is very hard to open especially if the filter change was long time ago.
Also for closing this wrench is very convenient. The thread of the screw is very fine. The nut must be hold exact even. You can but the nut in the wrench. Thanks to the design of the wrench the nut can't fall through! The wrench also helps to hold the nut even when closing.
If you want it stronger (normally not necessary) you can scale the z-dimension or change the infill.
Wall thickness 1.2 mm, PLA is ok.