i save my crumbs (or confetti) in plastic baggies, sorted by 'general color'....i.e., i want all the greens together so they can 'blend'...and have enough to do something with...altho i do have light green and dark green.... when i finish cutting all the pieces i need for a quilt, i trim the scrap of all its weird little points and add that to the tiny pcs from in between the previously cut quilt pcs. then i pile them on an 'unused' area of my mat (the better to spread the wear) and just slice the whole pile a dozen times or so, moving the rotary cutter back and forth and around the little pile. mix with fingers and put in the right color baggie.
i have all my baggies on a large 3" ring thru hole punch holes in the corners... zip shut till ready to use...then take out ALL the color you want and remix (this gets the color more even from all the different additions you have made.... spray background of picture with basting spray... now sprinkle carefully each color, one at a time, sprinkling and then pressing onto the sprayed area a bit to hold...cover ALL glue ... extra pcs will come off so shake lightly in between colors so you can put leftovers back in correct baggie. now do next color and so on.... i use simple blocks or simple coloring books...really primary books so they are simple line drawings... trace onto light fabric and start sprinkling...now put dark tulle over and sew along outlines and detail lines to hold all in place.....OR just FMQ in the same color thread....stippling to hold down...i have done both...they both work well.... i use the FMQ method mostly for the simple coloring book pix for little kid's bag trims, t-shirt appliques, pillow tops, etc., it's tougher than the tulle...