This was a really fun (and easy) felt onesie project I made a few months before my due date. I originally found this DIY project on Pinterest (love that site!) which lead me to this blog: Finley & Oliver. These make great baby shower gifts as well!
I created the graphics on Illustrator, printed them out and traced the images on Heat N Bond fusible webbing. Then placed the fusible webbing on top of felt pieces and pressed them together with an iron. After this, cut out the felt pieces following the traced lines. Pull the sticker paper off and place on the blank onesie, press down the felt images with an iron, fusible side down. Then simply use a sewing machine to secure the edges and add any extra stitching to complete the artwork. I recommend checking out Finley & Oliver for instructional images (I didn't take photos of the step by step process).
Make sure to trace any wording backwards on the fusible webbing as it will need to flip over onto the onesie (fusible side down).
The Kite Onesie in action!