I use Alumilite resin as you are probably aware. With Alumilite I do not have to worry about what cups because it does not dissolve the regular plastic silo cups. That said, I usually mix and pour 19 ounces at a time and therefore need a large cup. I use the mix and measure cups from the paint section at Lowes. I use a spatula to get most of the resin into my mold and then I rinse the cup out with Acetone. I pour some in, swirl it around real well, and then pour it out. I then pour a little more in and use a paper towel to wipe it all clean. Works great and is not a mess at all. Here again, this is Alumilite, though so I am not sure how PR would work out.