Tom here, I just wanted to open up the topic of what solutions are being used moving forward to solve design issues.
In your demo video you have mentioned locking mechanisms that will be much smaller for use in the final product. Could you go into further detail as to what they are and provide a link if it is an off the shelf product.
Have you considered using electromagnets to hold the arms in position? A solid iron rod spanning across the width of the display with individual coil clusters for each arm might work a treat and hopefully cut costs.
You could remove the teeth from each arms design and replace that with a metal coating. When each arm reached the correct position we could fix the arm with the magnet.
The next question is how you are planning to slide the arms back and forth, what will you use to actuate that movement? Watch this video i might be or interest :)
Are you planning to use something like self lubricating bearings so that movement will remain smooth for a long time without more than simple cleaning maintenance?
Has there been any consideration given to how to track the extent of that movement?
Anyways that my brain dump for today.