I have some old Pipeworks (https://en.wikipedia.org/wiki/Playskool\_Pipeworks) toys from when I was a kid, but apparently lost the wrench to disassemble them. The outer diameter of the pipeworks set this will work with is 1.675". This wrench works much better than jabbing two pens and asking another person or child to help pull it apart. Enjoy!
pipeworks_wrench.stl is the base file I used (printed version shown)
pipworks_wrench_notched.stl has a strengthening fillet at the joint and a couple of grips to look more similar to the original wrench
I printed with PETG to have flexibility to snap over the pipe with rigidity to push nubs in, but PLA/ABS/etc. should all work, too.
The author hasn't provided the model origin yet.