I was thinking about this again earlier and in a sense I don't think there is such a thing as an intermediate project. I think once you understand how steel moves you've pretty much got the knowledge of how to tackle any skill level job, just scale up your ambitions - tools and facilities pending though.

Fair enough that's a bit of a sweeping statement not intended to be taken completely literally, but is it such a leap from forging a hook to forging a heel tenon in a gate? It's the same material, just a bit chunkier, reacts the same with a bit more of a whack.

Sadly on this forge, the burners are just two holes in a pipe, not sure how I would adjust. 

I like the idea of rivets. I think making things consistently sized has been a struggle, so trivets might be a great way to practice those reps!