A close friend of ours made her husband's wedding band many years ago. She did this when she was working at a high school, using the jewelry-making equipment in the art studio during her off hours. She had a piece of aluminum lathed to the diameter of her husband's finger, and then wrapped bands of wax around the aluminum blank to build up a wax ring. The ring was then cast in gold from the wax pattern she had built up.
Fast forward many years to the present day. Not long ago, her husband lost this ring. I don't think it would offend anyone involved to say that her husband is her property, and that she had every right to put another ring on his hand as a signal to the rest of the ladies in the world that his is taken. She wanted to recreate the original ring, but she couldn't find the equipment to do this. In addition, she didn't have the measurements from the original. She made a drawing of the ring and worked out the likely dimensions of the original. Then she got a piece of jewelers wax and a ring-sizing ream from a jeweler friend. She started making a copy by hand, sawing off a piece of the wax and reaming it out. She didn't have a way to cut the outside diameter of the ring precisely enough, so I offered her the use of my lathe. She brought her accumulated jewelry paraphernalia over to our house, including a framed photo of him in which the ring is quite clearly visible. We measured the ring in the photo with a micrometer, and used a Bic Pen in his pocket for scale. We found a real Bic Pen of the same type, and solved for X to find the width of the real ring. Unfortunately, the estimate we came up with was quite different from what she remembered the true dimensions to be, probably because of lack of precision in the photo (which, parenthetically, we discovered to have been Photoshopped because the ring is on his right hand and his hair is parted on the wrong side, but his colleague's name tag appears to be normal. Sneaky.). So we went with her recollection of the ring's measurements.
We mounted a piece of the jewelers wax in the lathe and bored the inside diameter to match her husband's college ring that is known to fit well. Then we cut the outside diameter of the ring and two grooves, slightly radiusing all of the right-angled edges. I was worried that heat generated by the cutting process would deform the wax, so we held a piece of ice against the workpiece while it was spinning. Between cuts when we were discussing proportions, we hung a bag of icewater over the headstock of the lathe to keep everything cool and dimensionally stable.
The first ring we manufactured just didn't look right. Our friend came to the conclusion that it needed to be thicker--it was too thin (2mm)--and that the proportions of the three bands around the circumference needed to be changed to make the center band wider. She was right. The second iteration was about 3mm thick and the outer bands were reduced by .3mm each. Additionally, we made the outer bands of very slightly smaller diameter than the large central on. These changes made a huge difference in the ring's aesthetics.
The next day, she took the wax pattern to our jeweler friend to have it cast. He told me that:
1) This was a big ring (her husband has very large hands).
2) That we could come and work for him if our day jobs don't work out. I was particularly flattered that his normal wax pattern guy was slightly offended that he (our jeweler friend) had used someone else to make this pattern, until our friend told him what I do for my day job (I am not a jeweler).