I wanted a better brush cleaner than a sour cream container so I decided to design one.
My first version was a single water well but realized that I didn't really want two separate water wells one for dirty water and one for clean water so I made a merged one that has 2 wells attached by the brush holder ring.
I was going to put a grid in the bottom to let you clean the brush against but it would be way to hard to clean the settled paint out of it so I went with rings that are 2mm wide and 3mm apart, it works very well and is easy to clean with a bottle brush if needed.
I printed mine out of PETG so I could clean it with hot water without it softening.
If you use this for anything other than acrylic paints I suggest that you print it in a chemical resistant filament.
The clean water well is smaller than the dirty water well as once most of the paint is out of the brush the clean/rinse water doesn't get that dirty that fast.
There are two versions of the clean water well, I made one 1mm smaller around as one of my printers was printing it a little bigger than it should so that took care of that. (the ends of the half moon points were coming out a little too long.)
2 walls and solid infill to make it be a bit more solid.
I actually ended up doing two processes with simplify3d the first one was 3 perimeters and solid infill as the bottom with a single wall did not connect to the infill and stopped at 2.3mm height then went single wall 100% infill just to make it more "solid"
I had some issues with the filament under extruding and leaving miniscule holes in the corners of the crosshatch of the infill add enough of them up and it leaked pretty well. You may want to do an over sized first layer to stop any leaks, also what I did after fixing the filament under extrusion was to change the infill pattern from 45, -45 to 45,0,45,90 to add some vertical infill and it is really water tight now.