Paint Mixer
thingiverse
Jason has a great design, I modified it to use a 3/8" threaded rod to beef it up.
Download Model from thingiverse
With this file you will be able to print Paint Mixer with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Paint Mixer.