I've only done some crazy quilt blocks to use for bags. I used poly satins, velveteen, etc. I did sew on a muslin foundation, then "quilted" with the decorative stitches on my machine.
I did go to an Original Sew presentation years ago and the speaker was about crazy quilts--she made the point that you always start out the center with a piece that is odd #--i.e. 5 sided--that allows you to build out without it looking like you are just "off" on your quarter inch seam!
I have a crazy quilt that my g-ma made (she made many)--it is made as one large one, without descernable blocks. She used wools, dress fabrics, corderoy, some velvet, etc. Not sure if there is a foundation but suspect so as so many different weights of fabrics. Then she hand embroidered fancy stitches along the different fabric edges. The whole thing was then tied to a flannel sheet blanket--very heavy! ( no binding, it was birthed). I suspect this was the way her Mom did it too as she made many like this.