I use large snapware boxes. I bought a stack of 4 at Costco around Christmas that came with cupcake inserts- tucked those away somewhere and keep my sewing projects in them. I also have 13x13 scrapbook project boxes which I use for big blocks.

Labeled ziplocs, pop or beer flat boxes, pizza boxes, boot boxes, donut plastic boxes, whatever I can upcycle for free!

I keep the quilt tops in a Rubbermaid tub under my cutting table. I love making tops but really drag my feet on the quilting. sad, I know. the tops aren't keeping anybody warm from in that tub! I vowed to finish 6 by june. I have the batting and backs. just so scared of getting another fat "bird's nest" of thread again when I ATTEMPT to FMQ. I tied and stitch in the ditch the last few because of that problem and not knowing how to correct it. oh and they do sell 2.5 gal zip lock bags if you wanted to keep tops in until you get to finishing them

I'm with you. I will never BUY something if I can find something usable in the junk pile. I use used pizza boxes when I can find them. After I have cleaned up the inside as much as possible, I put in a layer of freezer paper, to make sure any grease will not get to my project. These boxes stack perfectly on the closet shelf, and are labeled at the edge so I know what is in them at a glance. Some of them have a "list of ingredients" LOL

I used to use zip lock bags. I had trouble storing them. They would slip around. I now use clear plastic craft boxes. Works great for me.

I have each quilt in a tubbie or a tote bag. It helps keep all the blocks and fabrics together.

Pizza boxes?? You ladies are brave...I would worry about smells getting into the fabric and attracting bugs.

I use 16 qt clear rubbermaid bins for work-in-progress, and also to store fabric together that I'm accumulating for specific quilts. I use post-its to mark what each one contains (although it's pretty easy to tell from what I can see inside, usually). While they're empty they stack together in my closet, but usually most of them are full; I have a table that they stack up on against the wall so I can't "forget" about anything. Raw fabric goes in there; when pieces are cut they go back in there. Unless I'm using a flannel backing, I can usually fit everything for a quilt (except batting) in a single tote. Makes it easy to work on a specific project!

I don't have this problem as I never work on more than one thing at a time. I usually have a quilt to the "sew on the binding stage" and maybe another I'm piecing. I only make charity quilts for kids. So sometimes I do two at a time. I only buy the fabric I need for what I'm working on. So no stash storage problems. I save the scraps from each quilt and when I get enough I make one out of all that.
I know, you can say it, I'm weird in the quilting world.
SVAL

I am trying to be better organized in my small sewing space (that's the plan anyway) and I purchased the extra large zip lock bags, which most grocery stores carry, put all the fabrics, pattern, magazine, in one bag. It keeps me from using a fabric for one project for another project, losing the pattern, directions, etc. So far it's been working for me, and here's hoping I'll be better organized and less frustrated.

I, too, use plastic bags, but have some (we won't say how many!) in the heavy plastic zippered covers you get when you buy pillowcases, sheet sets, or other bed linens. They are very sturdy and hold up well. As others have said, labels, instructions, and notes are very helpful, as well as putting in any specialty rulers or templates. Sometimes my notes include web addresses where I can find instructions or tutorials for a particular technique or block.

Hope you find a system that works well for you. It can make all the difference between ease of effort and frustration.