It would be an interesting exercise to write a Second Declaration of Independence and a Constitution of the Second Republic. The Founders got a lot right, but they missed a few things (the role of the courts and term limits to name just two). And wording needs to be sharpened up. Imagine the Second Amendment just saying: "Neither State nor Federal government shall pass any law which places any limits on ownership or possession of any weapon by any person not incarcerated." Or something to that affect. I'm sure I didn't get it perfect, but let's make RKBA as explicitly broad and untouchable as possible.
And given a chance, I'd like the Constitution to state that the Koran is not a religious book and Islam is not a religion and neither are legal within the US.