For the past couple of weeks, I've been using these little plastic containers from the Dollar Tree to keep track of my bow tie pieces and the 1 1/2" strips for my little bitty trip around the world blocks.
They're not large enough to hold many pieces, but I've got bigger project boxes for that. These are just the right size to keep pieces ready to sew when I've got a few minutes to sit down at the machine. They stack nicely. And they come in different colors. Because one of these days I might remember which project is in which color box.
What do you use to keep your little pieces together?