I use a single sheet of mesh but roll it into a 45cm diameter cylinder so there are far less joins to make and the trap is ALWAYS right side up.

I stick on two mesh funnels at each end and it is complete!! Actually I use a length of copper wire as thread to SEW the ends on and close the single join seam. You dont need to do this but I use many fish traps at once so it makes for very efficent transport and storage as I can undo and lay them all flat. I do pre-make the funnels which also stack. It takes me 2-3 minutes to make and bait a trap.
Whatever trap you use, try to have the mouths pointing parrallel with the water current not at right angles. Watch the bottom carefully and placing traps near likely fish cover or understanding the behaviour and habbits of the fish species you target will greatly improve your successes/