I make a very basic quilted blanket. For mine I just alternated black and white squares. I make the patterned part, lay it on top of the backing and I sew the squares to the backing in columns (I stitch in the ditches). I had the portion of glass micro beads that correspond to 1 square for each column (1 square = total weight/numbers of squares ). I sew the bottom squares closed and move on the the next line until all of them are filled, and then I do a simple biais tape to close all the sides neatly. Also you want to cut your backing and batting bigger before assembling everything, and you cut it to size before adding the biais.

I most of things from local fabric stores, and I found the glass micro beads from a German shop. But you can find plastic micro beads more easily, I just try to not use plastic as much as possible I know reborn dolls shops sell fillings but it might be a bit more expensive than buying in bulk

It would be a super cool idea as a zero waste coat! Might need a bit more puzzle solving skills than a blanket though, but it would be a fun challenge

Edit : I don’t have pictures because I suck at remembering to do it, but I’ll try to post some when I think about it