https://www.youtube.com/watch?v=o6TfhWY6WoI
A launch video notes that the new “Paint Preview” app includes all the familiar features of the regular version of Paint, but Microsoft is adding in 3D object support — an ideal addition for HoloLens. Paint Preview users will be able to create 3D objects, and annotate them freely.
Microsoft has a range of markers and art tools to help artists create objects, and brushes that can be used directly on 3D objects. All of the tools appear to be pen- and touch-friendly, with an interface that mixes 3D models, 2D images, stickers, and community tools for 3D content.