It floors me when I see people who fold their ball caps like they were books with a perfect seam.Here is one sure way that you can achieve a nice curve in your bill if you so desire.
You go out and you just bought a brand new hat. If you don't want to put any crease at all in the bill of your hat that's alright, it's your preference.
Step2
If you do want and evenly bent bill you first get a regular sized softball.
Step3
Having a rubber band handy, put the softball under the bill of the hat. Secure a rubber band around both the softball and the bill of the hat so that the bill of the hat folds around the softball.
Step4
Add several rubber bands in the same manner as the previous step to secure the bend.
Step5
After 2 or 3 days remove the rubber bands and the softball. You will then have a nice bend in the bill of your new baseball cap.
Tips & Warnings
For different degrees of bends you could use different size balls. For example: A women's softball, tennis ball, or even just a regular hardball.
Remember the smaller the ball you use the more extreme your bend will be. So be careful because once you use this method it is hard to change the bill back.