Originally Posted by Glenn

It is a plastic sewing awl. A spool of thread is placed in the well and the thread is thread out of the side hole in the lid. A sewing machine needle is inserted in the the top of the lid. The machine needle should have a flat side like a 15X1. The needle inserts the top thread thru the fabric and a second thread is inserted in the loop formed on the underside of the fabric. It is the same as a leather sewing awl. I have one but only used it once. It can be handy for small seam repairs.
Skiper