The ornamental design for an attachment to create and maintain a curve in the bill of a baseballstylehat, as shown and described.
FIG. 1 is a perspective view of an attachment to create and maintain a curve in the bill of a baseball style hat, showing my new design;
FIG. 2 is a front perspective view of the invention;
FIG. 3 is a rear elevational view of the invention;
FIG. 4 is a left-side elevational view of the invention, the right-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view of the invention; and,
FIG. 6 is a bottom plan view of the invention.
The broken lines showing a baseball style cap in FIG. 1 illustrate environmental matter and illustrate the invention in use; the broken lines form no part of the claimed design.