I found that that these pipettes work great for portioning out paint and thinner in fairly reliable quantities. For small paint jobs, one pipette of paint with one one and a half pipettes of Mr Leveling Thinner usually works well. For larger jobs, three to five pipettes of paint to 6 or 7 thinner works. For detail painting, at very low pressure (10-12 PSI) I will slowly add more thinner. I always test before spraying it because I occasionally get it to thin or too thick.
You can get these pipettes very inexpensively on Amazon. I think I got 1000 for something like $10 U.S. The other thing that helps me is the plastic container (cookie jar style). I keep these in front of me just above head level and it makes it easy to get them and use them as needed.
The Buffalo is coming along fine John (@johnb). Everytime I see this posting, I think about pulling out the one I have. So many kits, so many choices.