All the Commander cubes I've seen were 500+ cards. Since my playgroup is often 6 or less players, I tried to design a compact format with overlap between archetypes and cards that fill more than one role.
The intent is to create a space where there's a strong focus on the commander(s) and the players can express their personality through their picks, keeping at a minimum the number of cards that are obligatory first picks.

Draft: 3 packs of 20 cards each (4 packs of 15 each is also viable alternative).

Decks: 60 cards including the commander(s), the color identity rule applies. (suggested 25 lands)
Partners: the legends that have "partner with X" also obtain the other partner in the same pick. Players can freely include one or both cards in their deck as they see fit, the usual rules for deckbuilding apply.
Sideboard: there is no "sideboarding" per se (the games are best of one) but every card that a player drafted and didn't include in their deck is considered in their sideboard. Cards outside the game can be brought in (with Fae of Wishes for example) bypassing the color identity rule.

Games: starting life total of 40 life, up to 6 players, best of one.
In 6: 2 pods of 3 players free for all
in 5: one large free for all game
in 4: same as with 5 players or 2v2 two headed giant

List:
41 cards x color
45 colorless
70 multicolor (6 x guild)
40 lands