This is a snapshot of my old separable cube's retro section as it stood in 2014 when the cube stopped getting drafted as much. I had drafted this cube with folks at my LGS store throughout much of grad school and then times and cube tastes with newer friend groups changed and this cube fell out of favor.

The concept was that this retro cube could be extracted from the full cube by checking expansion set symbols. I chose the cutoff for the retro cube to be the end of the reserved list era, so it consisted of anything printed from Alpha through Urza's Destiny. All cards used were first printings, so no memorization tricks were needed to perform the separation (although some of my younger drafters didn't always know which symbols corresponded to these sets). The resulting pool of cards was large enough to support up to 6 people. We also drafted it a few times where the separated sections each contributed one of the three packs to the draft, which was interesting in its own way.