This is an inexpensive copy of the Reverspective principle originally developed by Patrick Hughes. See As you walk from side to side past the image, the image moves in a startling way, as if it were following you. Copyright 2007 Off The Wall Art John Davenport purchased it from for around £12.

The disc has a small ball bearing in the centre of its base. When the disc is spun on a flat surface it therefore spins for a very long time, creating amazing optical images as the prismatic material on the surface catches the light at different angles. With a bright light shining on the spinning disc from one direction a 3D effect is created. Made in England.

This is an amusing way of dressing up the optical effect when a person stares at the centre of a rotating spiral disc for 20 seconds or so. When the person then looks at the magic mushroom, it appears to grow or shrink, depending on which way the spiral was rotated. Made in China for Worldwide co,

In addition to the optical illusion image on the mug, the writing on the mug’s box is cleverly done to make your eyes go squiffy when trying to read it – just take a look at the picture of the box. Made in China for Paladone Products Ltd, Shoreham-by-Sea, West Sussex.

If you spin the top, when it settles down to spinning horizontally the pattern of colours look like flower petals. The picture at the bottom right of the instructions gives the idea. Purchased by John Davenport from Kohfuh Satoh at the International Puzzle Party 31 in Berlin in 2011.

Viewing the Christmas tree card through the special spectacles which consist of blazed-gratings makes the red decorations appear in the foreground. If you are interested in the physics behind this effect there is much information to be found on the web. John Davenport purchased the spectacles and card from Tim Rowett at the International Puzzle Party 31 in Berlin in 2011.

A set of four coasters which form changing moiré patterns when rotated. The best way to see the effect is to put a coaster on the table where it is held in place by its non-slip base. It is then easy to use your fingers to rotate the top part of the coaster to reveal the ever changing patterns. Bought by John Davenport from Grand Illusions in October 2012. Made in China for Kikkerland Design.

A lithophane is an etched or molded artwork in very thin translucent porcelain that can only be seen clearly when back lit with a light source.The images here show the same lithophane lit from the inside and from the outside. This lithophane is illuminated by a night light inside. Purchased by John Davenport in Hamburg in 2013.