[Mr. Miyagi]

I don't know about everyone else but I like to tune my return pipes to be silent and bubbleless. Issue is I have to turn my valves on my returns about 10-20% closed to do this. About once a week lately I've had a few snails make their way into the pipes. Once overflowed my display and once I was lucky to be in my equipment room when my pump started cavitating so I threw both valves wide open and out popped a snail... so here is my solution:
First I marked out some pvc to fit into my elbows as long as I could fit into my overflow:

Then I went to a hobby store like hobby lobby or Michael's and got some mesh that kids use to make stuff with yarn. You will find it by the yarn FYI. I used zip ties to secure the screens because it's reef safe, strong, and looks clean:

Then put the cap on the bottom without any glue, just not needed, and fished them down into my overflow.

And it actually made it easier to tune with my valves also!

 

[Mr. Miyagi]

Forgot about cost. Had the pvc, 2 end caps were .98 each and each sheet of the mesh was .69 and it took one per side cause I wanted to make sure it was large enough surface area to never clog.