I was having a PM with a member and and I sent instructions I had written for making a sampling nets. If you are interested, I use two different sampling nets.
I explain how on to make a collapsing sampling net in this Wisconsin TU newspaper article. The collapsing handle is a magnet from Harbor Freight. The article is on pg 8. There is also a second article I wrote on how to make a New Zealand strike indicator.
I also referenced the following posts I made on the fly fishing forum. If cross posts to another site are not allowed, please remove.
Here's how to use a paint strainer to sample the drift for hatching insects. I carry this in my vest also.