Last weekend I helped our friends Jason and Jen over at Humphrey-House who are nearly finished enlarging and remodeling (and "greening") their kitchen. I brought over some color swatches and helped them pick out some great colors. Then, my years as a builder/remodeler came in handy as I showed them how to install level cabinets in an older house .
Since the floors of older houses are so NOT level, a clear tube with water is the answer.