Not the prettiest for sure, but I am a big fan of a backpack and a crate. All my bike parts/tools live in the small front pocket of the backpack. My work stuff fills up the main pocket. When I ride, the backpack goes in the crate, but when I'm off the bike the backpack is super easy to keep with me.

Bonus - When I need to carry extra stuff, my backpack goes on my shoulders and i can fill up the crate or tie stuff to it.