The bridge. On the AOP823, it's welded more on the "face" of the frame. It's rounder, and this is the reason the bridge looks thicker from the front. Also, it pops out a bit more and has a forward tilted angle. I don't know by how much.
The frame. The 823 is slightly thicker, and the edge has a subtle rounded bevel. Not only that, it is slightly curved around the lens, thus helping make it look even more thick. Eyewear wire comes in different widths, but these kinds of things aren't generally described. I had looked into eyeglass wire a bit back then and couldn't find the standard wire height/widths for rx eyeglasses. It may all depend on the eyewear company.
The lens shape. There's a lot to unpack. One may think that because the lens height on the IM replica is 3mm more than Walt's actually is, it's why the lens shape isn't all there. I recall commens made by some other users, maybe it was squidman and westies14, about my drawn attempts ending up looking "boxy," and after Indy Magnoli had a prototype, the frame having an "aggressive" look. Even I thought that one was odd, but I understand why that happened now. In my honest opinion, the replica being 3mm bigger is not or only why it looks boxy. I suppose I should have asked what exactly was meant by "boxy."
In the beginning, my attempts at drawing the lens shape resulted in a further boxy looking shape because of how I was drawing the lens. I went through multiple methods to draw it and they all resulted in the same incorrect shape. I thought it would've been corrected a bit with the base curve/wrap and the forward tilt. I thought that if the anchor points were placed appropriately, that if bezier handles were carefully moved, that if the lens was drawn almost pixel by pixel, it would result in the proper shape, but...no. And it's not because I (nor Indy Magnoli on his own attempts) didn't try to get as close as possible, but because there's something else going on with the lens shape of the 823. I don't think the shape was created using modern day eyewear design guidelines.
Those of you who still have the design drafts Indy Magnoli posted may see the lens shape, a box, and a circle. This is typically how modern eyewear is designed, and the curves that make the lens shapes start at the middle of the box edges – top edge, bottom edge, outer edge. Prior to the replica, the Hilco (AOP's parent company) SG301 was a frame I called the most accurate to Walt's eyeglasses, and I used to believe it was Walt's eyeglasses but updated. Some of you said it looked 'boxy.' Given that I now agree, I would say it is because the SG301 follows that modern eyewear design guideline where curves are drawn from the center of the lens box, and because the sides are straighter. It has diameter of 56 and 49 mm. I own a bronze aviator frame with the supposed correct dimensions of Walt's eyeglasses of 54x43. I will say that despite the right lens size, it didn't look like it because the dividing point between curves was at the center of the lens box. That frame also had a diameter of 56 and 49 mm too. The point for mentioning the diameter is that, for whatever reason, it appears to be a standard for a similar lens shape even at different lens sizes. It's on that aviator frame, it's on the SG301, it's on the AOP823, and it's on a frame I have with an entirely different lens shape and smaller size. So the diameter, even having it right, doesn't help create the proper shape of the 823 if the lens is still drawn incorrect.
When I did my attempts at drawing the shape, I didn't consider the radii, only after the replica was created. When I did, I did get closer, and as closer as I thought it was, it still wasn't. What WAS considered was the correct anchor point placement from which to draw the lens curves from. I don't remember exactly what was decided for the replica, but 2 of them (the ones on the sides) were almost correct, falling within a 1mm margin. Proper anchor point placement does help give a more accurate shape. See below.
On the left, you'll see a boxed lens. It is 54x44, with diameters of 56 and 49 mm. It is wrong because it was drawn from the center of the box.
On the right, you'll see another boxed lens. Same size and diameter. The anchor points were shifted from the center correctly. The curves have their own anchor points placed correctly at the diameter. It is still wrong. Illustrator, like I presume many programs, creates curves with right angles. Anyway, you may say it has a "puppy dog" look – the boxed right one – as westies14 once said about Walt's glasses. Correct anchor point placement – shifting them away from the center – is a way to get that look.
On the top left, you'll see a complete frame drawing with a lens size of 56.2x43.2. Still wrong shape and all, but it has the same circumference as the replica, and was me working towards a better version.
To the right of it, you should see the closest shape I've drawn so far to the AOP823 going off an image of my own. It has the circumference that's on Indy Magnoli's - 165mm. Size is 55.85 x 42.85.
Below it is what Walt's glasses should look like if they were 54x44mm and closest in shape. I can't compare anymore with Indy Magnoli's replica since I popped up the lenses on that one last year. In the photos below, my IM replica has a size of 55x42.
Achieving the curvature and shape of the 823 is not difficult, it simply needed more time, and a good reference.***
*** — It was kind of impossible to get the correct shape from a still from the show. On some of the pics I uploaded you may see a bit of why. Camera distorts things, especially vertically, more so at certain angles and perspectives.
What I am going to try to do is have the Indy Magnoli replica re-lensed to have the proper shape of the 823 at the expense of a slightly bigger size. I believe it is possible. Lastly, what I've learned is that rx eyeglasses have a standard base curve of 5 degrees, a forward tilt of 10. Some are even rotated. Last one is why Indy Magnoli's prototype had an "aggressive" look. They're rotated on the 823 as well.