Original Polydron Colour Mixing Cube

Six tiles, a stand, and one very good idea. Build the cube, hold it up, turn it — and cyan, magenta and yellow slide over each other into greens and reds and blues that weren't there a second ago.

It's small and it's cheap and children stare at it for ages. There's no instruction needed; the turning is the activity.

Suitable from age 4. Dishwasher safe, BPA free, and fully recyclable.