Review on Optimize Your Mixing Ratios with Custom Shop's Calibrated Solutions by Jojo Howell

I find them particularly useful for measuring and mixing resin, plaster or polyurethane foam for my model railway layout. The beauty is that they're affordable, have exemplary quality, and their dual function (measuring and mixing) saves time. Even my 72 year old eyes can easily see increments in ounces. As an added bonus, the developers have provided helpful markings to make it easier to mix two to three ingredients in the recommended ratio. For example from 1:1 to 8:1:1.