This piece is one I folded a couple of weeks ago using the same approach as my recent luminary. On the outside of the form, I drew a small spiral of a pattern in ink, which gives a hint of what is on the inside. The inside is painted and has two more patterned spirals.
The shape of this form creates interesting patterns of light and shadow when the model is lit. Near the middle of the model, the section just below the crease line that slopes away from the light appears much darker than the section just above – if the middle of the model flared out much more, the outer part would actually be in shadow. Also, the pattern drawn on the outside appears much crisper than the patterns drawn on the inside. Here is a close-up of the patterns: