Each image is a scrambled set of dual-image random-dot stereograms. Unlike the single-image stereograms found in many popular 3-D art books, these are the old-fashioned kind that use one image per eye.

To solve the clue, cut out the individual squares and find the pairs of almost-matching squares (the random dots at the edge will be the same, but some dots in the middle will differ). View each pair as a stereogram by laying the two squares next to each other separated by an inch or two. You can use either the wall-eyed or cross-eyed viewing technique (here are some helpful hints). There is a pair in the middle of the first page if you want to just try that one instead of cutting out all the squares.

Each pair has a single bold letter standing out or receding (depending on your viewing technique and which way you laid out the pair). The pairs on the first page contain M, O, U, E, and two S's. The second page contains T, A, N, and K. Answer: MOUSE'S TANK.

Clue author: Walter Smith