Just wanted to post the build I finished and tell all the people wondering if they can build an omnium themselves that it's totally doable without much experience. Just patience, loads of tutorials and reddit/fb discussions.
I started joining a self-managed bike workshop, helping them with what I knew on bikes (changing chains, tyres ...) and when I had time using their tools to build the bike. It took a few weeks between ordering the frame, components and mounting but now it's done and I'm proud of myself. Even built the wheel from the rim. Build is not perfect so don't hesitate to tell me if you see something horrendous. The red plastic thing behind the seatpost will be removed, I haven't assembled the dynamo yet and it's a part of it.
It's a pure joy to ride this bike ! Have fun all
