Here is a real quick video showing how I do my acrylic application step in the construction of a retainer. THe method is call " Salt and Pepper" because of the alternating application of the monomer (Liquid) and Polymer (Powder). I have also heard it called "Shooting Acrylic" which I think I like better!
I get my Polymer and Monomer from http://jbcandcompany.com/
Check out www.DesginerRetainer.com for more information.