Most Buckles around here suffer from either moving parts or even worse, parts that are bent and will break after some usage time.
I had this problem several times with replacement parts for buckles of Ortlieb bags.
So i decided to create a buckle, that has no moving parts. As it is symmetric, it may be connected to handles or belts fitted with this buckle, too.
The buckle prints nicely without any supports.
The buckle was designed using OpenSCAD, you may adapt some parameters to fit your needs.