The FlexLinks Cross-Axis Flexural Pivot produced by the BYU CMR group (https://www.thingiverse.com/thing:2987817) is a delightful mechanism, and they have cleverly made it compatable with Lego Technic parts, as well as manufacturable with a laser cutter.
At the moment the most suitable filament that I have for the FlexLinks is PETG. In order to work well with PETG, I must print the first layer closer to the bed than optimum, which makes it spread out ("elephant foot"). This means that when I print the STL files from https://www.thingiverse.com/thing:2987817 I find it hard to fit in technic pins without trimming the bottoms of the holes.
Presumably in order to make their design work well with Laser cut sheet material, the BYU folks decided not to make the flexLink STLs the same thickness as the equivalent technic parts. This allowed them to avoid having to make the recessed lip present on standard technic holes.
I have previously developed a set of openSCAD tools to make lego parts (https://www.thingiverse.com/thing:2738552) and decided to refactor the Flexlink parts in openSCAD.
This allows the width of the flexible segment and the size and positions of the beam segments (with the holes) to be varied. The pieces are the standard thickness of technic pieces and have the standard stepped rims (at least on one side). This allows me to print flexLinks that do not need to have the holes trimmed, even though "elephant foot" is present.
I have not gotten the ends of the beam segments as nicely curved as the BYU folks, but maybe that is a feature, not a bug, since it makes it easier to tell the difference between the two versions.