1. Miniature score, or the things marching bands use to clip to their instruments
2. 18 x 24 sketchpad (x2 when you open the book for a two page spread)
3. Adjustable. 0 - 90 degrees would be nice.
4. grand, vertical, organ
5. on top
6. be secure. You want it to stay in place even if the page turner uses it to prop up their elbow.
7. Something light. Maybe it could fit in a typical keyboard bag.
8. Aluminum, magnesium alloy, carbon fiber reinforced plastic. Whatever, as long as it is light yet does not compromise structural stability.
9. Some stands fold back, others fold forward. It would have to work on both.
10. It would be wise to keep in mind sightlines with conductors or soloists while using the stand.
Some people like to stack their music on the stand. The pile could grow to 3 - 4 inches thick with books, especially when hymnbooks are used.