Take the sheet with the quality you want and measure a pattern that you like for the bed, for overlap and tucking under etc plus two inches.
Cut it and on the machine my wife has for monograming has a foot that gathers and folds over and stitches a sealed hem. Got something to lay it on before and after and it wouldn't take five minutes per side or ten with much caution.
With a King or Super King or whatever it is called you would have enough material to make at least tow pillow cases. Then set the monogram pattern and have fun. I can do it but wife keeps butcher knife around the coach and I can't run that fast any more.