You can test the thread by taking some and wrapping around your hands and pulling. If it is strong enough to kind of cut into your hands before it breaks, it is strong enough to use. You have a treasure trove there! If it can't be used for machine sewing, it can be used for hand sewing. The little cardboard bobbin spools are perfect for hand applique and great for take along projects. The spools that are wooden would look nice in a clear glass decorative jar for your sewing room. I am sure board members will give you lots of ideas.