Woodworking/Carpentry. As much as I like writing code and working in Product, it'd be nice to work on something tangible. It's so much easier to give someone a physical product that (for the most part) is 'done' when it's handed over, and there's also the knowledge base that remains mostly intact and isn't continuously iterated like it does in programming.
It's cool watching someone I knew at uni build something that's useful for so many people, especially seeing him pop up on Hacker News from time to time!
Maybe start by looking at a small problem/time sink you're currently facing and build something around that? For example, I wrote a small script in Python to automatically scrape jobs in the past 24 hours when I was applying for a new role (It return the Company, Job Name, and Job Link).