That's damn fine ... however I do have some (qualified) criticisms...
Mainly it seems to be very wasteful of space and of time (and bricks). If you want a conversation piece and something impressive to display, and you have room for it, then it's all good.
Otherwise, I can't help thinking something more akin to yer old 45rpm jukebox rack would be more practical. All the discs lined up in a single horizontal row, you only then need to locate by distance along the rack, and the disc is plucked from or dropped into a simple groove in an L-shaped holster. Separation distance just enough to get the gripping jaws in - or if you have a ton of actuators to spare, they can be almost touching, and the relevant disc is pushed proud of all the others by a small lever, easily grabbed without even having to dive into the stack.
Pretty sure I've seen actual commercial high-density disc changer systems that work on that principle. This looks more like a high-grade backup tape library robot system, but turned inside out... (normally the picker would be on the inside of a cylindrical chamber, surrounded by an endless wall of tape holsters, and a small stack of actual drives)
Still, if all the bricks you had were ones that allowed you to make this and not the other one... party on.
(Now, upgrade it - make one that accepts jewel and/or DVD cases, and can both open them and retrieve the disc from within, and also replace disc in case, then close and store said case... and can keep track of and deal with multi-disc games/cases...)