Step 1: Gather Supplies
5. Cutting Device
6. Something to catch. (for pride!)
Step 2: Size the String...
Leave about 1" or so hanging over the edge of the bowl.
You will tie two knots in the string. One knot will be in the middle of the string and the other will be in one end.
Step 3: Tie the Knots...
Double the string in half and tie the bait loop as shown in the pictures.
Pick the longer end of the two, because you most likely were unable to center the bait loop, and tie the same knot to form the nail loop.
Celebrate because you have completed all of the work for building this mousetrap!
Step 4: Bait the Bait Loop...
The bait should be placed in a way that the loop and bait stick up. Mice tend to grab on to what they are eating and then sit up on their back feet and munch away, much like a squirrel. So, you want that bait loop to be sticking up as much as possible, so that when he grabs the bait, he pulls the string.
Step 5: Now the Tricky Part...
Double the free end back toward the bait, and which will allow the bowl to rest on three total points. Two string points and the nail head.
I suggest that the string be first placed so that it is too short to support the bowl, and the tip of the nail must be angled in. Then, use the tip of the nail to draw the string under tension bringing the nail toward vertical. The goal is to have the bait string taught so that the slightest tug will cause the nail to fall.
Like I said, this is the tricky part.
Your girlfriend/sister/mom will ask you what the world you are doing because you will drop the bowl repeatedly trying to get it set.
Your boyfriend/brother/dad won't care what's going on so long as it isn't during the Cardinals game. =)
Step 6: A Few Tips...
Also, make sure that the surface is hard enough to allow the nail to slide. Granite counter tops have voids and gaps between the grains, and the nail catches in these, saving the mouse for another day. Wood cutting boards allow the nail to penetrate, which also favors the mouse.
Good luck and let me know if it works for ya!