@AnimuVsMango Ball has a very established katakana writing, ボール, which would mean tugeneko wrote it wrong or differently on purpose. Just seemed kind of unlikely to me. It
is possible ball was the root word of the pun/joke, but I still wouldn't know what to change it to for English. Even if I used "Tunnel Ball," something about it would feel wrong if it ignored the fishing rod angle. I usually try to make the titles sound like something you'd actually call the invention shown as best I can.
@Oeconomist I did find quantum tunneling when I was researching for this title, which explained the use of the word tunnel. Unfortunately, it doesn't amount to much of an invention name in line with what I've been using for most of the chapter titles, so I decided not to pursue that direction.
Also agreed, Minamine is great. Her chapters always make me laugh.