Cut a piece of wallpaper to the size you like.
Fold “accordian” style…like you did in school. Press down on pleats with your fingers to form a sharp crease.
Bunch one end together and secure (hot glue or whatever works for YOU).
Spread “pleats” open till they look how you want them to.
Decorate the gathered end with ribbon, small fabric roses, beads, whatever you like. Attach a piece of ribbon to back to hang on wall.
This may take a couple of tries….. as the size and pleating technique you use will differ the look… however it is VERY simple and VERY quick.