Learn a trick or two and apply it to your future sewing projects.
Turn the fabric right side out, then insert it under the jeans with their seam edges matching.
Flip the fabric right side out, and poke the corners nicely.

Image Credit: Tale Handmade via YouTube
you’re free to also use this method for an easy pillowcase.
*All these images are credited toTale Handmadevia YouTube.
4 Clever Sewing Tips and Tricks

