This is my little boy who is 4 months old
I made him a shirt made from cotton fabric using my sewing machine and I made the measurements from a T-Shirt of his. It was just a practice run really, the fabric says pick up truck on it and has a truck.
I got a bundle of fabric purchased from eBay.
I also found this YouTube video very very good which shows instructions (for my Brother model sewing machine) on how to sew buttonholes and buttons onto material.