Overlays I would instantly buy: Similar to the existing one but with a slit to stick a paper in (so it doesn’t fall out every time you raise the overlay).
Additionally there could be several kinds of such overlays to chose from that differ via their magnet signature (e.g. Innovator Overlay I, II, III, IV, V etc.) - which can be distinguished by the Morph as usual.
That way we could easily create several swappable overlays ourselves without having to have a 3d printer.
Another very interesting overlay would be a very thin overlay with a adhesive side where we can glue stuff on (e.g. neoprene material with prints on it etc.). Have printed several neoprene overlays but they don’t stick to the Morph…
Optinally also with several magnet signatures to choose from.