Over the years, I have made several quilts with non-cottons/garment scraps. Sometimes it surprises you which ones wear better and which shred to pieces after 20-30 years.
Suggest you don't go for a "precision" block, i.e., stick to squares & rectangles rather than triangles. Poly blends do not press a crease really well.
I did one quilt using two different widths of blocks, maybe 6" & 8", each width had 3 sizes of rectangles plus it's own square. Garment makings from the early, mid 80s, so it was autumn, golds/oranges/rusts/greens/blues.
6"x 2", 4", 6", 8" and the same thing on the 8" width.
I did alternating columns the length of the quilt, laying out the blocks on a work space, so they never shared a seam. Used a very thick batting, tied along the columns seams. Did a japanese style wrap around backing to front to form an 8" mitered binding. I just googled that style of border, and don't find anything. My mom had a book...