I was able to catch mine in just a couple minutes like this-
1. get a water bottle (size of bottle depends on size of tank and space to put it)
2. remove label as best you can
3. cut the neck part of the bottle (an maybe an inch of the body of the bottle)
4. Put the neck you just cut off back into the bottle but the other way
5. punch a small hole in the bottle and tie fishing line to it.
6. bait the trap (mysis or whatever you feed your fish)
7. wait...........
8. when the shrimp goes in the trap pull it up with the fishing line. the force pulls the shrimp down so it is unable to escape once you start to pull. Also the it is harder to exit because it is hard for the shrimp to get back through the opening in the top