If you want to learn to build something, build something. Register a domain, build a site and put it live. Iterate until it's something you're actually proud of, then use it as something you can point to and say "I can build sites like this".

That'll get you more credibility in front of a future employer than any number of years experience sitting in a cube doing Enterprise Java stuff.

Pick a tech you want to work in, work in it, then find a way to get paid working in it.