I have some of the zip bags that blankets come in. They work great for lots of things. I have several kits i made up stored in them. The only thing i wish was different is the zipper location for ongoing projects like blocks of the week/month. I looked at plastic project boxes but i prefer smooshable storage. So, I found these:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
They are perfect for me and large enough to store lots of fabric along with storing blocks flat but smooshable for those projects that don't fill them up.. Although they are mostly fabric, the clear window is great for viewing and, the best part, they are cheap! Lol.