To finish the connecting rod I calculated the angle of the slanting top and bottom of the fork and marked them.

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Initially, I had only marked one side but then I realized that it would be better to mark both sides.  Put it in the vice using a mark one eyeball method to line it up with the top of the jaws and proceeded to mill them off.

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After some clean up this is how the fork end looked.

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Next, the crosshead pin. For this I used a piece of 0.375" stainless. I did the screw first (sorry but no photos) and then the other side. Drilled a 3.3mm hole and counterbored it 4.5mm and then tapped 4mm.

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Then the size of the shaft was reduced so that it will pass through the fork. I used the fork as a gauge.

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Flipped it around and faced it off and, using a pointed tool, I marked the centre of the face.

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I did this so that when I put it in the milling vice it would be easier to locate the centre. Used a 1mm end mill to cut the slot, but managed to break it. So instead I used a 1mm slitting saw to cut the slot.

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And this is how it looks with the crosshead installed in the fork.

Drawings here

Part 15 here  Part 17