If I were this guy (on Ebay) I'd probably go about it the same way, however fruitless it may seem. The best ideas are just that - ideas. Anyone can steal an idea with or without a patent.
I agree, I would do the same. Plus, He is supplying some materials. Which means he did not create any new trapping hardware. He took something he had lying around the house.
If he patented it, you would see it in the store and say, "I could build that out of a coke bottle. I'm not going to pay $15.00 for it!"
I Still think that if you are going to go through the trouble of keeping it a secret you need to find a new avenue. Keeping your feedback private on ebay seems sneaky.
Think about how many people are out there with a fish they do not want to disassemble their tank to catch. I have considered buying this product several times. That **** Pseudo-chromis loves to pick on my other fish.
Then think about the people who have posted on this thread for what is now 4 pages. Free Advertising!!! All curious as to what it is. If Dr. Nate never tells us what it is, will you guys go buy one to tell the rest of us? It is only five bucks. This hobby costs so much money, I bet a lot of people buy it just out of curiosity.