I am probably wrong, as I almost always am, but I think that the collar pictured above is a fraction of a millimeter taller than the collar of the original robot. The original appears to be slightly less tall, as this screen grab suggests:

One of the most beautiful collars I have ever seen was created from scratch by Craig Reinbrecht. Craig has achieved the perfect profile for his collar ribs. More important than the profile, I admire the way Craig designed a collar that is structurally identical to the original collar. My club-made collar is probably superior in design and strength, but like a moth to a flame, I am fatally attracted to robotic authenticity.

The thin aluminum channel can then be connected to the rim of the torso in a very elegant and efficient way.

Here is a good shot of the aluminum channel with the attachment pegs in place.

(photograph courtesy of Craig Reinbrecht)
Here is a shot of the latches, bolted to the neck of the torso of Craig Reinbrecht's robot. The pegs that protrude from the aluminum channel in the collar slide into the notches.

 

These are the latches that Craig designed.  They are bolted to the torso and then cut with a channel to receive the attachment pegs.

(photograph courtesy of Craig Reinbrecht)
 

In the back of the collar, there is a thin bracket that receives a screw. This holds the collar firmly in place when mounted to the torso. Here is a picture of this device in Craig Reinbrecht's robot:

The original robot had this same feature. Major West can be seen unscrewing this element in preparation for removing the robot's collar and head assembly in the first-season episode "The Hungry Sea" (episode 5, original air date: 13 October 1965).

I hope that this discussion has given you a hint of the amount of work and dedication required to create a beautiful and elegant collar. Craig Reinbrecht achieved this. I hope that I can too.