i remember making little bows/slingshots when i was little! i think we just did them like pillowhead stated. just a straight stick with notches and twine. my ds has been begging for one as well. i should get busy! lol
for the slingshot(i think i may still have one hanging around here somewhere!) we used a little oval "pocket" made of leather with two holes punched in the ends for braided leather or twine to go on for the strings. this is a "real" slingshot, like the kind you hold the two ends put a pebble in the pouch and swing the ends, the let go. they can get pretty dangerous tho, so i haven't given mine to my ds yet. lol i can still remember my mother lecturing us when we were little, "remember david brought down goliath with one of those!!". lol
we did the other simple kind with a "y" stick and a thick rubber band. we also made lots of rubber band shooters to play with out of wood.
i wish i had some pictures. maybe if i can find the slingshot i could post a photo if anyone is interested.