I'm Currently sewing machine'less so I cheated a little and brought a ready made pillow slip.
I wanted it to look like a pirate flag so I Google'd pirate flags for inspiration then hand drew the image to the size I wanted it.
I hand stitched around the outline it was very tedious work at times I felt like giving up, but I'm happy with the way it turned out in the end.
Oh this was for part of the skull swap :D

*Big thank you to Laurel S for the photos