It is slightly different from the video as I have modified and improved it since then. Here is Jacky demonstrating it. First time she ever tried it!!
Step 1: Items Needed
Four Pushbutton switches (momentary ON) - Radio Shack 275-1566A for the square one pictured. The round ones are better but I don't have the number. The other difference is that the round ones have screw-type terminals (better) and the square one pictured has solder-type terminals. If you will be moving it a lot you may want to get alligator clips as well.
Small gauge wire - Radio Shack 278-1218. I found afterwards that a couple different colors helps to keep everything straight.
Step 2: Items Needed
7/32 or thicker plywood, enough for four 10" by 10" squares
Aluminum trim - 80" (eight x 10" strips) optional but helpful
Foam padding - four 10" squares. Should be firm but slightly flexible, and an inch or so thick. I was lucky enough to acquire some gym floor padding which is carpeted on one side. Sports Authority sells workout floor squares that may work just as well.
Rip-Stop nylon (2 yards)
Various hardware (screws, drill, soldering iron, knife, saw. glue gun, staple gun)
Step 3: Make the Pad Base.
Cut a 10 inch square from the plywood.
Hot glue four small strips of the foam to the corners at an angle. They should be about 1/2 inch thick. This provides the cushioning for when the pad compresses. Ignore the traces of padding that aren't in the corners. Those were other positions I tried but didn't work as well.
Drill a hole for the button and attach it. (The button pictured is slightly different from the one in the items step. Get a round one if you can find it.)
Step 4: Attach the Trim
Attach the strips of aluminum trim on the top and bottom of the back side of the base. The protruding edges (perpendicular to the board) should be 10 1/4 inch apart. This has to be spaced firmly to fit on the frame bars.
I also marked "R" on this pad so I'd know to attach it on the Right side.
Step 5: Place the Foam.
Place the foam on the button side of the pad base. When you press down on the center, the button should depress and make its connection. You can vary the thickness of the underlying foam supports if you need more or less space.
Place a velcro strip on top. This has to be long enough to wrap around the frame bar and secure the pad. This pic is wrong! The velcro should be perpendicular to the aluminum strips, not parallel. Check the next pic.
Step 6: Wrap It Up.
Turn the pad over and place on the Rip-Stop nylon. I also added a thin strip of padding on the aluminum strips so it cuts down the noise when it strikes the frame bars. You can see the terminals where the Ground and controller wires will attach.
Staple the nylon to the plywood. Leave enough room at the top of the aluminum strips for the velcro to come straight out so it can wrap around the frame bar.
The wrap should be firm, but not too tight. There has to be some give for enough motion to release the pressure button when not being pressed.
Step 7: Wire the Controller.
I bought an after-market controller for the Sony PS2. This one has the added advantage of being able to see through it. You can see where I soldered one wire each to the connection under each button. This is good enough for the DDR game. In fact, you only need to do the ones on the right side. I didn't bother with the analog controls, or the Start and Select buttons. This makes the controller still useable by itself.
There is also a Ground connection on the right and left side of the control board. Solder a wire to those also.
It is difficult to see, but there are actually five red wires coming out from each side of the controller.
Sorry for the lack of detail here, but I really didn't want to take it apart again to risk loosening a connection.
Step 8: Pigtail the Ground Wires.
Don't forget to label the wires or you will really get confused!
Take the two ground wires (if you did both sides) and pigtail them together with another wire that will go to another pigtail that will go to the pads.
Step 9: Set All Ground Wires for the Pads.
Take the single "out" ground wire you just added, and pigtail to four more wires that will connect to one side of each of the pad switch connectors.
Step 10: Wire the Rest.
This looks nasty but is pretty simple, really.
The bottom eight are the eight wires from the controller. I'm not currently using the four from the directional arrow side (up,down,left,right -- the left side on the controller), so those four on the barrier strip on the right are not connected to anything.
The four on the left are from the circle, square, triangle, and cross buttons. You can see they go "out" to the four green wires, which connect to one terminal of the pad switch.
You don't even need the barrier strip if you just wire from the one side of the controller. You could just run the wires directly.
You also see the pigtailed ground wire with the one going out to the blue pigtail in the previous step. Those four wires go to the other side of the pad switch.
This completes the circuit.
Step 11: Attach to the Frame.
Wrap the velcro strips around the bars of the frame and you are ready to play! Use the controller to choose your style, character, and song, then punch the front pad (which corresponds to the "X" -- or hit the "X" on the controller) and punch away!
I made the front one the Down arrow, and the top one the Up arrow. With this setup, you can actually do a solo two-player game, using the hands for player one and a regular dance pad as player two. I think I will airbrush the arrow on to the pads to make it a bit easier to follow.
Creating the frame is a whole 'nother process. I wanted something sturdy enough that you could whack pretty hard, but still be portable, and adjustable for people of various heights to be able to play. Still working on getting it just right. If you just want a home version for yourself, you could just make the basic frame out of railroad ties or something heavy.
If you don't make a frame, you could make it sort of a Whack-a-Mole game instead.