RowdyBetta - You rock!
I picked up a sheet of plastic mesh today (for less than a dollar), cut it to size, and sewed the edges together.
I made three of these tonight, and all three of my fish went straight into it!
Of course, my 4th guy is jealous. I'll get to his tomorrow.
I don't know if you trimmed the edges, but I did this, since I didn't want any sharp parts to catch on their fins. But it worked really well. I thought I had monofilament (nylon) fishing line but I couldn't find it, so I used regular sewing thread instead. I wasn't sure it would hold, but it worked just fine!
Yay! My guys have a new toy!
(Well, three of them do. Tahiti will have to wait until tomorrow to get his.)