I needed a small container to soak my speedball rollers to remove acrylic paint.  I wanted it have the smallest volume possible to use less paint removing solution as possible. It’s why I didn’t want to just use a mason jar.
 

Definitely use Murphy oil soap to clean your brayer roll.  It loosens the paint in less than an hour. The box is handy because it allows you to use less soap and then save that soap and reuse it. 

This is the revised and fixed version of this brayer soaking box. There are two different soaking racks. The clipped one is less filament and no supports. I did end up using a little epoxy on the joint to make it stronger but works fine without it. The other is stronger and easier to use but needs supports. I would print the rack at 100% infill. I've noticed that water seeps into the rack if there are any voids. 

Petg worked great for this model. 

The clip came from this maker: https://www.printables.com/@levisitts