A small set cube of 405 cards. The rarity distribution is 3x or 2x per common, 1x per uncommon, 1x per rare and 1x per mythic. The strongest commons are 3x. Some rares and mythics have been removed along the curve to help the asfan in packs closer reflect retail draft (very difficult to recreate at 405). Also, cards at all rarities that are total stinkers in limited have been removed. Rares removed along the points in the curve for their color that were most over-represented, and some commons bumped to 3x not based on power-level but to boost a low point in the color's curve.
I built this to onboard newer players to limited, while also being something my normal cube group could get behind when we were feeling the need for something different. My main cube is a 360 Vintage cube, and other members of our group have Pauper, Peasant and 93/94 Cubes. We don't have a set cube in the rotation yet. My Vintage cube is not a good place to learn limited, much less Magic in general.
I chose Dominaria for a couple of reasons, as opposed to a more traditional Set cube expansion like Innistrad. I started playing Magic back around Tempest and Urza's blocks, so the plane itself resonates with me. I also wanted to avoid things like double-face cards in this cube (I support them in my vintage cube, but this is supposed to be easier). There is a chance I decide to build a Plane cube someday, so Planes like Innistrad and Ravnica that have many blocks I wanted to leave open so as not to have a bunch of overlap in my collection (All the old blocks from Dominaria feel more like I would be building an old border cube rather than a Dominaria Plane cube, so that doesn't really count to me - I do understand there is a disconnect there). Lastly, I enjoyed DOM limited, which is as good a reason as I can think of.