Here on the NE coast you'll often find foam lobster buoys washed up on shore.
Tourists might collect one or two good ones as home decorations, but I find they're just the thing for building poppers....even the broken ones
I use a saw to cut them in to slices the length I want my popper bodies to be, then punch out cylinders with a jig make from a sharpened piece of copper pipe
Keep your eyes open for different colors. I have white, yellow, orange, red and blue.