First pass… No bird yet
The manufacturer’s model has some discrepancies from the actual item, chief among them being the slot for the lever extends further than it should. So that’s why that looks off.
There’s a weird shape to the end of the angled transition between the ring band and the underside of where the iris attaches. It seems like there’s a curved shape to the notch at the upper end but I don’t think I have that quite right.
I set the thickness of the window frame plate thingy to 0.5 mm.
Are the diameters in the manufacturer model correct? It has outer diameter of 0.825 in., “front” inner diameter of 0.474 in. and “back” inner diameter of 0.497 in.
Oh, and I actually used that set of ring sizers from the McCoy med scanner for their intended purpose! The finger hole for this ring has a maximum size of about a size 9, leaving a band thickness of approximately 1 mm. The outer diameter of the iris puts an upper limit on the size.