Yeah, a plastic bottle is a good start. Cut the top off, leave the bottom, then cut a small hole near the lip and poke a thin twig through it for a string. Tie the string to a weight or a small rock and hang it in a shallow spot. Drop a little bait, let the fish think it's a free buffet, and hope it bites. Keep the design simple so you can build it in five minutes and not spend a lot of time fixing it.