How Many Blockchains Have You Built?

I'm very curious about what that process is like building a blockchain. I've built the vast majority of the, at least the earlier versions of the C++ Ethereum chain. And if not, directly programming on it's very close to the parity Bitcoin implementation. It's pretty cool. Like you can open it up to the public, you can start to get users and by very virtue of it being a network they're connecting with each other.