I took an ordinary white-plastic Bic pen and removed the "guts." Then I cut the end at an angle a bit greater than 45* and put a notch in the lower end. I did this because I'm trying to handle the fish I catch as little as possible and because I'm cheap.

I have a couple pics, but they aren't too good due to the pen being white inside and out. I do have to sand this one a bit with an emery board before it gets used on a real fish. (I lost the last one I made, but who cares because it's so cheap?)
EDIT: Oh, yeah--a smaller diameter tube would work better, but I can't find anything stiff enough.

I ran into some that were made out of darning needles...they were pretty neat also...I made one out of a pencil once when I was having a interesting day and lost my forceps...also dunk my phone...got stuck in a mud bog...caught 1 snapper and cut my new furled leader trying to let it loose when it lunged at me...also had the car not want to start..twice...Yep, interesting day

I was thinking what a good idea and what would be a smaller piece of plastic. Then I thought of the sleeve that they put food(and A/C) thermometers in. I am a cook so I have a few laying around at work. I'm going to make one soon.
Marion

Well, I'm at work and the sleeves to put the thermometer in is just as big as a pen.
I'm going to keep looking for something about 3/16" diameter.

Nice idea, I could never warm up to spending 20 bucks for the store bought model.