Not particularly meant to be used, but if for some reason your a messed up person you probably shouldn't look at this. Please be very careful because as killerk said this gun is very powerful.
Disclaimer: anything that happens because of this is in no way my fault. it is your choice to read and construct this item.
Step 1: Gather Materials
All you need:
KillerK Basic Knex Pistol
A door or door way
Step 2: Tape Gun to Wall
tape it onto the door frame make sure that the projectile can come out
Note: also make sure the trigger is facing you NOT THE WALL
Step 3: Attaching the Trip Line
wind the wire around the lower hinge of the door and then up to the trigger on the gun and make a loop
Note: the gun must be higher than the lower hinge so it gets pulled down
Step 4: Setting Up
Load the projectile( a few wall nails)- cock the gun- hook the loop- crawl under- close the door