Halved paint scheme with bone as one of the colours
I'm not quite mad enough to start a third Marine army, especially one I couldn't actually paint, but it's worth noting this would be a significantly more viable army to play now than at its inception. While the Hammers missed the absolute peak of the Iron Hands' meta-warping power, and certain Firstborn marines remain best-in-slot, you can put together a very decent all Primaris army thanks to all those releases over the last couple of years.
Something like a mix of Plasma Inceptors, Plasma Redemptor Dreads and Intercessors (Dark Angels Combat Patrol Box) with Bladeguard and Eradicators (ideally from an Indomitus half), and some subset of Primaris Apothecary, Techmarine, Chaplain, Lieutenant and Captain would be an incredibly solid all around force.
Edit: depressingly few hammers in such a setup though, unless you load up the Intercessor sarges.