Remix of the pin and main body y1 for Sandeagle's “PrintClosure Project”

This is a revision of pin.stl, which is used to connect the parts, and of the part “y1.stl,” in which a bore diameter is incorrect. I have flattened the pin so that it can be printed lying down and offers maximum strength. I have also added a small chamfer. In y1.stl, the bore is now 3.2 mm.