Inspired by DonaldJ's simple design https://www.thingiverse.com/thing:647835 and forced by the fact that it didn't fit my print bed, I designed a simple rack with a twist (a 45degree twist) that just about maximized my 6x9 print area. Minimal layers and minimal infill, I'm trying 2 and 10% on my first print, hopefully will be enough.

Edit: Came out very durable. Fit is close but not tight. Also made a simple drop in holder for brushes https://www.thingiverse.com/thing:2736871