0.2mm layers, it's all top/bottom so infill irrelevant. PLA+ fine.
I've included my Fusion360 file in case anyone needs to tweak the size again, although you'd need to adjust the spline part of the sketch for the rounded beak ends too.
The author remixed this model.
Once I'd trimmed a bit off the original's jaws to make it easier to remove, I realised the OD of the part it needs to fit on my couplings ( https://www.amazon.co.uk/dp/B07DGLCJ4Z ) is 5.3mm and the original is 6.7mm so there was a fair bit of movement.
I couldn't easily adjust the original model as the Freecad file isn't compatible with my Fusion360, so I imported the STL as a mesh and sketched a new component with the dimensions I needed, and that's what this remix is.
I didn't have to do any adjustments after printing, this just clicks in place and removes nicely when required.