I'd make 9 patch blocks, set them on point with Black as the sashing. Or, just mix them all up and sew them into a quilt. If you want something a little different, then applique balloons or something as a center focus.
This is a pretty airy pattern that would go together really quickly with four inch squares. Of course, you would need a lot of background. [url]https://www.pinterest.com/pin/566679565586171033/[/url
I like this one in a scrappy version, with each different block a focus on a single color palette. https://www.pinterest.com/pin/566679565586171016/