He’s using an Arduino Mega to drive the 7x7x7 cube ... straightened by stretching the wire. The 5mm Blue LED’s are positioned 30mm apart, with the anodes being attached to the verticals ...

Instead of the relative horror of driving 40 LEDs with a single Arduino, [Martyn] bit the bullet and got a Maxim 7221 LED driver. Controlling 64 LEDs over a three-wire interface simplified the ...