Boil the salad macaroni in salted water, following package directions, drain, rinse, and cool (you may want to drizzle some olive oil on the rinsed macaroni to keep it from sticking together)
Chop onion, & bell pepper in large dice (1/4" or so), and stir into cooled macaroni along with olives
Mix sour cream, mayonnaise & celery seeds together and dress salad. Salt & pepper to taste.
Place in a large bowl with a lid or a large aluminum pan & cover with foil, and you're ready to go. The salad should NOT be left out in the sun, but I've left it out for a couple of hours with no ill effects to those who've eaten it..
The salad can be made in advance (allowing the flavors to develop, in the refrigerator, of course)