I love Steeveet's condensed Splendid box for Splendor - it's the best design I've found, and inspired some boxes of my own for other games. I like to include a reminder of the rules in the bottom of my lids, so I don't have to look up details or carry around the instructions - for this one, the number of gems and nobles in the game dependent on the number of players.
They can be read as:
(Reminder to always set out the max number of gold gems, per the rule book)
I've also added the Splendor label on two sides of the base, for easy identification in your game shelf. This base is Steeveeet's “Base.stl” file - not fit for sleeved cards.
The author remixed this model.