Alexander Calder inspired mobile - tissue paper and wire. This may be the answer to my mobile dilemma. I found corrugated cardboard is too hard for kids to cut. Thin wire and tissue should be a bit easier.
L'idée déco du dimanche : des tableaux déco découpés dans des toiles - Floriane Lemarié
DIY "Floating Bookshelf" Add two tiny nails just under the brackets. Open the bottom book, and used the nail to hold the cover closed. This hides the bracket completely, making the bookshelf invisible.