I have made picks and plectrums from just about everything including ring pulls from beer cans (great for the autoharp by the way) to single teeth cut from a nylon hair comb in an emergency. As i invariably break at least one thumbpick and one finger pick at every gig, I always carrry one of my out of date cards with me as well as bits and pieces of broken or redundant guitar /banjo parts which are handy in an emergency. Best of all were a set of picks made from a hammered flat coke can using a set of metal ones as a template. Great once the blood had dried up. Learnt my lesson for the second set and folded the top edges over.