all you need is some felt (i bought sheets of felt at Michaels for $.20 each) 
hot glue gun (this could also be easily hand-stitched) 
the length and width of your felt depends on how big you want your bow tie to be. mine was 12 inches long and 1 1/2 inches wide, with a smaller strip that is about 1/2 inch wide and 2 1/2- 3 inches long. my little guy is one and this size is perfect for him, and i think he’ll be able to wear this size for a few years. (i like smaller, more proportional bowties, but if you like them bigger just make your strips larger.) 

how to:

1. cut one end of the longer felt strip into a point. lay the felt strip on a flat surface and bring the pointed side across the strip about 2/3 of the way. 
2. turn the pointed side over and bring it back across the other side until it touches the edge.
3. adjust the point if you need to, it can touch the edge or hang over a bit, whatever you like. 

4. scrunch the middle of the felt together, making it look like a bow. 
5. wrap the smaller felt piece around the middle of the bow where you scrunched it, with the ends meeting in the back. 
6. turn the bow around and dab some hot glue in the center of the bow, then fold the top end down over the glue. glue down the remaining flap, making sure the bow is tight and secure. 
and then have fun with them!

To turn it into a bow tie I usually thread elastic through the center of the back of the bow tie, but if you don’t have room you could glue elastic to it or sew/glue it to a pin or clip.