I use artist’s acrylics to weather rolling stock and mentioned to my daughter (a born shopper) that I had broken the piece of plexiglass I had been using for a palette. When I described my requirements, she took me to the candles in the home decoration area of Target and pointed me to their ‘candle plates.’
Voila!! For less than $5, I have a circular clear glass palette with a slight lip around the edge. Works great and cleans up easily with hot water. Ought to work equally well for other paints that come in a tube (oils?).
Chuck