Recommended for mixing epoxy
On page 5 of Russell Brown's e-Book "Epoxy Basics", he states:
You will be mixing many batches of epoxy. It helps in many ways if you get the right cups and sticks, and learn how to do this part well.
We think of epoxy as liquid gold. Properly mixing it is like adding value.
To mix all the epoxy in your cup, you will need cups with straight sides and a flat bottom, and stir sticks with straight edges and square ends.
With this combination you will be able to scrape the unmixed epoxy off the sides and bottom of your mixing cup, so that your whole batch gets mixed together thoroughly.
Try snipping off the tops of the cups with scissors. This makes a sharp edge you can scrape your mixing stick and other tools on, keeping epoxy inside your cup, and not running down the outside. Try it, you'll like it.