If you need it to be an arduino, here is source and circuits for an Arduino Due that works as an USB DAC.
https://github.com/Grix/LASDAC
It was used as prototype for the Helios DAC, and the Due uses a microcontroller in the same family, which is useful because it has a built-in 12-bit true DAC for X/Y signals. The extra circuit contains another DAC for colors, and correction amps.
But you might also just consider a Helios DAC itself. It can be connected to any computer, like a raspberry pi. And it is open source, both software and hardware, so you can just reprogram it to work as an arduino, outputting directly from the microcontroller instead of being controlled over USB.
https://bitlasers.com/helios-laser-dac/