Step 1: Tools Needed
Metal you Can drill (I used Matal from an old Bike frame)
Flat head screwdriver
Normal drill (optional)
Hacksaw ( you may need it)
Step 2: The Hitch
Step 3: Preparing the Wagon
1st you might need to take of the handle.
2nd I recommend you drill holes for bungee cords on the sides of the wagon.
3rd I also think the trailer looks cool and is more obvious to cars when you put some flags in the back so... If i were you i would drill holes for flags in the back to.
4th I had to cut a small piece of my wagon off with a hacksaw... if something is bumping the tire you might want to try cutting it.
(all these drilling recomendations are for plastic wagons only. I have never made one with a metal wagon, though you could probrably improvise to get the bungee cords on there)