I actually started writing up a a new constitution a while ago as a sort of thought experiment. It’s not finished yet but some of the highlights thus far include:

• A unicameral congress, with uncapped membership
• A right to privacy, free education, internet, and government transparency
• Freedom from religion clauses
• Constitutionally limited intellectual property: Copyright is 15 years for corporations, life for individuals.
• Uncapped supreme court, 2 appointments per presidential term
• Score voting for the president
• Proportional representation for congress
• No term limits