A replacement cap for the Oleo Mac 937 chainsaw. Works for both oil and fuel cap. You can see a picture of the original.

You will need a O'ring for this cap (the same as the original).

Made with FreeCAD, you can see the source file in downloads.

Edit 2026-05-09 :
The STL model appears to be corrupted, and due to major update in FreeCAD I was unable to re-generate it properly.
So I remade it nearly identical with minor edits.