Consider enclosing a handwritten card or a printout with a lovely saying for your best friend. Write or print the saying on the white paper. Be careful not to take up more space on the paper than you can cover with the jar you want to use as a template. Then place the jar on the paper and draw a circle around your saying with the pencil. Do the same again with the cup on the pink card. The circle on the pink card should be bigger than the one on the white paper. Then cut out the two circles.
Place the smaller paper circle on top of the larger cardboard circle and use it to measure out a piece of cord that is also long enough to be used as a loop to attach the circles, which will later be glued to each other, to the cup. Apply enough glue to the pink cardboard and glue first the cord loop and then the paper circle to the cardboard. Then knot the loose ends of the loop together.