Do you have to keep getting up to empty the small cleaning container(s) you have on the workbench for cleaning your brushes after using acrylic paints. Here is the solution I came up with today to handle that exact situation. After cleaning my brush in a smaller container I just dump the waste water down the funnel into the bucket without ever having to get up.

I made the whole thing for around seven dollars with items purchased at Home Depot.

1) Plastic Bucket - From the Paint Department.
2) Matching Plastic Top - From the Paint Department.
3) Set of Funnels - From the Garden Department by the Fuel Containers.
4) Epoxy Glue - Already had some.

To assemble the container I drilled a hole in the center of the top using a spade bit. This hole is slightly smaller than the funnel portion I will be pushing through.
After pushing the funnel through the top, the plastic around the hole should have a slight inward look to it. I then glued the funnel to the top with epoxy glue and left it to set up. Make sure you push the funnel in far enough so the bucket handle will clear the top of the funnel. After the glue has set place the top over the bucket and push it down securely until all the tabs have snapped in place.

Below are two images of the waster bucket I built. I will need to put a drain hole at the top when it comes time to empty the bucket Ideally it would be nice to have a plastic valve for this.

Interesting solution but as I generallyt paint at the kitchen table with my back to the sink it's not something I need I generally use 3 or 4 jars cleaning thebrush in succession in each one so that the majority of the paint comes offf in the first jar and by the rinse in the last jar the brush is clean of paint. I can see how your solution would be useful if I had a dedicated painting area though.