I had the opportunity to play with this machine a few months ago, when Brian Corteil, a Cambridge maker-extraordinaire, brought it to a Raspberry Jam. It’s a piece of genius: the Naughty or Nice machine removes the guesswork from Santa’s assessment of the year’s behaviour, and applies the scientific method to the problem.

A palm rested on the reindeer-leather surface inside is assessed by tiny elves imprisoned in the baseplate, and little sleighbells, dangling from a festive holly wreath, tinkle a coded message to Santa to let him know whether the hand’s owner is naughty or nice.

(Actually, the machine takes a photo of your hand and counts the red pixels. This means that little people, with little hands, will come out with a much nicer score than us naughty grownups.)

Children I saw using this machine thought it was magical, and formed a long line – for once my “explain all the technology” instinct was subdued, and we just let them think the machine was driven by enchantment. And a Raspberry Pi. Brian’s made full build instructions available over at Adafruit – thank you Brian, and I hope Santa’s made a generous assessment of your own behaviour this year!