Recycled fabric baseball cap

I used the "hi" bubble for the button. It came out a bit off-centered :/

Here is my first attempt at making a baseball style hat. I used the denim scraps from turning my jeans into shorts, recycled happy bears fabric from a pillowcase project gone awry*, and piping made from recycled gift bag handles. The only new elements I used were some eyelets, a cover button, bias tape, and a small piece of elastic for the inside.

* I had used wool for the backside of the pillowcase - it shrank so much that the whole thing became distorted and unusable. The good news is that I now have a nice piece of thick felted wool to use for another project.

Note: Do not use stretchy jean scraps like I did, it gets easily distorted.

Question: How do you sew stretchy fabric/knits without distorting it? Different type of sewing machine/needle?

{Note to self: for next time, a shorter bill , non-stretchy fabric, and add a 1/2" to the height.}