Newton's cradle Mk 1 was a failure due to the design process being constantly interrupted having to let the cat in/out.

Schroedinger's cat, black L

Bad day detector: fix the wooden base to your dashboard. Whilst driving check that the ball is resting on the square of wood: if it is resting in the U-shaped metal frame then you should be forewarned that the remainder your day might not go to plan. This is also true if the ball is neither on the square nor in the metal frame and cannot be seen at all.

Schroedinger's cat, black L

Minimalist menu holder: just push the menu down and it is gently gripped between the ball and the wire frame. Hey, pop the dessert/drinks menu on the other side at no extra cost! If this is right I may just change my name to Mr Smug; in fact, I'll change it now! (When proved wrong I may have to consider Mr Mug as a more apposite soubriquet).

Ball appears to be marbled plastic with a wooden base, about 3 inches across and it appears to be placed on a faux leather bench seat not uncommon in diners.
Schroedinger's cat, black L