Directions to making a very usable arrow launcher.
Buy a sling-shot.
Buy a Whisker Biscuit. (fancy bow rest)
Zip Tie the biscuit (so it detaches to the rear)
Insert Arrow and fire.
You can get fancy and replace the leather pad with bowstring which locks/ nocks the arrow, that makes it easier and more accurate. Then add a loop for a trigger release and 2 guide strings to ensure even draw... But if you just want to make a dozen bows to arm your Elf militia...
I've tried this one and it launches arrows nicely 30 yards and will bury them in a target with enough force to make me believe it could do the job. As hard to aim as a regular unsighted bow but with practice...