You didn't say what your quilt is for. If it's for a bed you can always use the extras to make a throw pillow or a table topper to go on a nightstand. If it's a wall handing, use the extras to make a table topper or coasters. And, yes, you can add other colors to them. Such as, if the original is a wall hanging and you're going to use the left over 3 1/2" blocks for coasters you could put a bright 1" border around them. You could use the same color or different ones for each block. They could be regular colors or brights. You get to be the creator so create. Hold one of them up to your stash and audition each fabric as you move it around. See what jumps out at you and that's what you want to use.