Start with a couple of boxes of rainbow pasta. I also use mis-matched and every color. Use whatever you have and add to it to bulk it up. Cook, drain and cool the pasta. I do this well in advance so that it's totally dry. Even the night before is a good idea . . .
Hunt around the kitchen for ingredients. Use anything and everything. Don't forget to scour the pantry. My favorites are: cheese cut into tiny cubes, mini pepperonis, black olives, cukes, peppers, hard boiled eggs & broccoli florets. This is a great way to use the last bit of ham or the end of some other leftover.
Add fat free Italian dressing and toss to coat. Enjoy cold.