Here's a photo of one of my home made traps, I used 1/4 inch plastic fencing, just make the cylinder, then shape a funnel and an end and zip tie it together, I used a wood hoop from a craft store to keep the shape at the door end, also put a piece of metal stock on the bottom to weigh it down, I used aluminum.
The best bait for the trap I have found is beef liver.
I use the traps to check on the size of the trout, but also get mostly GSH and some pumpkinseeds.