Mark Mandell - Gone Round In New Jersey
I have a bag of used (recycled-clean) small solo cups like you get with takeout food. I have my buds save theirs for me. Make great mixing cups and I'll usually get 3-4 mixes out of one of them. Moisten a paper towel with DNA before the epoxy gels and the cup wipes out clean; no muss or fuss.

Do NOT add your bulking agent before mixing the hardener; it will be very difficult to get an even and proper mix of resin and catalyst that way and you'll be "asking" for uncured or partially cured epoxy. ALWAYS mix the epoxy first, then put in your addments.