The artist and model idea sounds great. Drawing someone is so intimate, and distant at the same time. It's also a wonderful opportunity for a 'clothed dominant / nude submissive' scene.

Alternatively to Egon Schiele's masturbation (...makes me imagine somewhat blurred pictures...) one could experiment with various uncomfortable and sexy poses.

For a submissive who tends to be fidgety, posing for a drawing must be a reeeeaaaally good exercise in patience and obedience.