[roc]

They also had no weight to them and what little weight they had was well-distributed.

Unless this hypothetical snap-bracelet device also had its weight very well distributed, it's going to tend to spin. Particularly if the total weight is sufficient to cause the snap-bracelet to slide toward 'open', even a bit, as your wrist rotates or travels through the air. And evenly distributing the weight over an entire-surface-screen would be quite a challenge, given the internals.

I think it more likely a production device along those lines would have a series of fixed potential-attachment-points and strong magnets to counter the forces caused by the weight of the device and movement of the wrist. And the screen wouldn't need to be over the entire device, but simply enough of the 'top' so that it could reasonably serve the various potential-attachment-point configurations. (the magnets would also provide a simple and consistent way to determine just how open or closed the device is)