Improvised ammunition for the r0ketlauncher, if you don't have enough foam missiles.
It does not get much more simple than this. A small piece of paper, ~3x~5 cm, rolled together and bent. No tape is needed, but that might reduce air resistance and increase range a bit.
Be sure to adjust the diameter of the paper roll carefully. It must be tight enough to not leak air and loose enough to slip off the launcher.
The range is a bit less than for the original missiles, but can still reach 3-4 meters.