Forks happen all the time: choose a block as a starting point, ignore the next block in the chain, and start mining your own blocks on top of this!
Forks and forking of cryptocurrency.
[Guide] Forking process of creation is fairly simple. It's simple to do with developers but what will happen with forked coins after all. If those forks are not attractive with Bitcoin community, they will not leave the longer chain and join forked chains. Without demand, forked coins from Bitcoin source code and Bitcoin blockchain will die.