https://www.modulargrid.net/e/antumbra-dvca
You'll have 4HP if you use the Cara marbles module, which is 2HP less than one you have in the top left.

-- Manbearpignick

but then you get into shitty ergonomics territory...

-- JimHowell1970

On the very long odds I could ever afford to build this, I've found a place that makes custom racks, and I'd be able to go bigger and use the proper-sized Mutable modules throughout. I've lurked in the Racks forums for quite some time now, so definitely appreciate the importance of ergonomics.

Thanks, @JimHowell1970.