Flatland Lock was never finished off  in the way I intended. It was meant to have a border of navy squares all round but works equally well without. These instructions are far less detailed than our usual patterns, allowing you to use any squares, of any size, in any yarn, in either knit or crochet.

It was  inspired by a puzzle in Leonardo’s Mirror and Other Puzzles by Ivan Moscovich. This is what it says in the book.

In the two-dimensional space of Flatland, the bank vault is an ingenious mechanism consisting of four sliding linkages which can move up, down, left, and right only.

The four black squares (ours are grey) are fixed at the corners of the rectangular vault and the sliding linkages cannot cross them.

The object is to remove in succession the four linkages, one on each side of the vault to uncover it completely.

Which piece must be moved first? How many moves will it take to open the vault?

To read more about the mathematics
Click here

To download the free pattern, read more about the afghan, and see more examples
Click here