A pauper cube, based on the definition that it's pauper if it shows up when you search commons in Gatherer. The themes are centered around the three-colour combinations, but the three-colour drafting isn't recommended, although it might happen if the stars align. Splashing a third colour for a few pivotal cards should be a lot more viable though.

The idea with three-colour themes in a non-three-colour cube is to make the decks synergistic and thematic, and not just have the cube be a pile of good cards, while still keeping the draft very open, and make it a possibility to find new ways to combine the themes. A possible risk is that the themes will be too vague and spread out, but that will require testing to find out.

Suggestions are appreciated.

The themes are: Esper - Fliers Grixis - Control Jund - Aristocrats Naya - Tokens Bant - Blink Abzan - Humans Jeskai - Spells Sultai - Graveyard Mardu - Weenies Temur - Defenders