3D printing filament is probably the highest-value product you could hope to make with your recycled fishing floats. So it makes sense that you'd want to produce it, and sell it to those people who feel bad about all the plastic waste we're generating collectively, and want to be part of the solution. But you have to understand that 3D printing filament is also probably the most demanding use any thermoplastic is ever put to, and that it already fails frequently in normal use from mysterious causes that people here on this forum are used to pondering at length. Adding the odd particles of shell, algae and sand just doesn't seem like it's going to help.

On the other hand, if it were easy, someone would have done it already. I don't want to discourage you altogether, but just to let you know what you're up against. If you come up with an effective pre-cleaning process, a way to filter out impurities and dehydrate your melted plastic batches, and could put it up into hermetically-sealed packaging, then sure - I suppose it could work, especially if you went for large-diameter filament that's less likely to choke on the occasional particle. It just seems that just about any other product you could make would be a lot easier to satisfy customers with.

Andrew Werby
www.computersculpture.com