The shrimp guns are the way to go. You can make your own for a few dollars. You need 3 feet of 2" pvc. 3 feet of 3/4" pvc. A small rubber ball with a hole drilled in the middle. A 2" cap. 2-3/4" caps and a 3/4 inch elbow. Drill a small hole for a bolt in one of the 3/4 inch caps and a 1"hole in the 2" cap. The bolt goes thru the 3/4" cap, the ball on the bolt, then a washer and a nyloc nut. This is probably getting confusing by now if you haven't seen one. Plan B, go look at one then put it together.

Also, if you have extra sand shrimp, cut the tails off and freeze them. Vaccuum pack after a couple of hours if you have one. Grab some kids and take the shrimp heads out to the sidewalk. They crawl around like battle-bots, the kids will love it!