...serious question: why can you not these days get marker-pen turtles for silly small amounts of money? (Or, indeed, at all?) Battery, wireless and sensing tec

...serious question: why can you not these days get marker-pen turtles for silly small amounts of money? (Or, indeed, at all?) Battery, wireless and sensing technology is now so easy and cheap that producing a battery-powered turtle which talks Bluetooth ought to be simple. You could use the works from an optical mouse for motion tracking. The old turtles got quite sophisticated, and eventually turned into plotters: https://www.youtube.com/watch?v=mR8enP09RPI https://www.youtube.com/watch?v=mR8enP09RPI (The hole in the middle was where you put the pen for turtle mode.) Look at those elegant curves as it draws straight lines! And you can see it calibrate itself against the edge of the paper. They made a later version with a longer cable but I can't find a video. Ah! There's a 1985 review of the plotter on page 28 of this: ftp://ftp.stardot.org.uk/pub/docs/magazines/beebug/volume04/greyscale/BeebUG%20Volume%2004%20Number%2002%20June%201985.pdf Man, I had that magazine when it was new...