I'm looking through the scales specifically associated with zodiacs that are clear enough to see some of the details (about 120 out of 500+). They range from c. 1009 to c. 1554. These are mostly in manuscripts, although a few are architectural.
Most of them have dowels, beams (squared-off dowels), or metal rods.
Some highlights:
- The early ones don't usually extend far beyond the cords/chains.
- Eyelets are seen in early medieval times in several regions (Spain, France, Austria, Middle East)
- Hildegard von Bingen's Libra looks like it might have a bolt through the wood to secure the chains. There are only a couple of others drawn to show bolts.
- By the 13th century, there seem to be more scales where the rod extends beyond the attachment point for the chains.
- There are manuscripts from Augsburg, Cologne, and Austria from the 13th century that are drawn with several cords tied over the top of the rod. This style is brief and not frequently seen again until the early 15th century in France.
- By the 14th century, some of the scales have bulbous ends.
- Hooks become more common in the early 15th century and eyelets are not infrequent, and increase in frequency by the mid-1400s.
- An early Middle Eastern Libra, and some of the German and French manuscripts from c. 1170 and from the 1400s show how the cords are spun together for an inch or two before separating into three separate cords.
An 11th century Arabic Libra, one thought to be from Italy, Vat. Pal. Lat. 1368 and Vat Lat. 3121 (also a later mid-16th c from Germany), are drawn similarly to the squarish top connector/spike on the VMS, as is another from Germany that came later (mid-16th century).
That's all the time I have. Gotta run.