Introduction: DIY Cardboard Mechanical Hand
If you haven't noticed already, this Instructable is to help you to make your very own cardboard mechanical hand. This is very simple to make, and the supplies are readily available around the house. Personally, I only used it for aesthetics after cleaning up the excess hot glue and painting it, but it can easily be used to pick light items up to avoid spreading germs. The reach can be adjusted, so long as you don't go too long and mess up the structural integrity of the cardboard. I hope you enjoy!
The supplies you will need for this project is a couple of drinking straws with the little bendable joint, some string (I used kite string, but you can use whatever is available), a hot glue gun with a couple of sticks, and of course 2 pieces of 16x6 segments of cardboard. The thickness of the cardboard doesn't matter, but I had sheets that were 2/16 inches and it seemed to work just fine. It should be thin enough that it can be bent for the knuckles, but also thick enough that it can hold itself up. Be warned, I am a 13-year old so you might need a bit of adjustment.
Step 1: Cutting Out the Hand
Take just one of the pieces of cardboard and lay it flat. When you put your hand on it, it should fit snugly on the sides when you spread your fingers apart. Adjust your hand so it is taking up about a foot of the cardboard, then trace your hand with a pencil, like you're making a hand turkey in second grade. I used my left hand so I can draw with my right, but you can switch them up if you feel inclined to. After filling in some missing spots as I did, edit your drawing so the fingers are rectangular and your arm is straight and not tapering out. It should look like the arm of a primitive robot, instead of a human. Make sure there are still some gaps between the fingers. Once you have drawn to your satisfaction, start cutting it out with an X-Acto knife or a box cutter. I got a pack of 2 from the Dollar Tree, and they last for a couple of months each.
Step 2: Mechanism Part 1
Now we start getting into the real guts of this thing. To start off, get a pencil and draw lines where your knuckles and joints of your fingers are. There should be 3 lines on every finger except for the thumb, which should have only 2. Once you're done with that, take a ruler with a sharp edge to make a crease wherever the lines are. Make sure these are VERY defined, otherwise the entire hand will not work. Next, cut out a 7 x 1 inch cardboard piece. Fold the edges towards the middle 1 3/4 inches from the outside. I used a pair of pliers to secure the crease, but that's optional. It should look like a rectangle missing a side. Now when you put it onto the lower arm part of the hand, it should fit almost perfectly. Glue it on there with a couple of dabs of hot glue and this step is done.
Step 3: Mechanism Part 2
This is the most important part of this project. If you get this right, you're pretty much done. So we'll start out by cutting our drinking straw into 17 1/4 inch pieces. Hot-glue 3 pieces onto each finger, the middle segment, the bottom segment, and the part on the palm. The top segment should be left alone for now. For the thumb, only put 1 piece on the piece closest to the palm but not on the palm. On the palm part of the thumb, drill a hole just big enough for your straw piece and glue it down. With your three remaining straw pieces, make a line towards the handle. Now cut 5 1/2 inch pieces. Glue one down so it is heading down the side of the handle and the thumb part is done. Then, put the rest facing the handle in the middle of the palm on the other side. Now, take a 6 1/2 x 1 1/2 strip of cardboard and glue it onto the wrist on the opposite side to make sure the wrist doesn't bend. Get your kite string and cut about 5 1-foot segments. Hot-glue the strings to the tip of the fingers and thread them through the straw until they reach the handle for all of the fingers. For the final step, cut the string until it comes to your finger and tie it to a zip tie as tight as your finger. After doing it for all of the fingers, you should be able to flex your fingers and the robot will flex too. I was able to pick up a couple of things, including a can and even a phone.
Step 4: Final Steps
So there you go! If you followed these instructions correctly, you should have a working mechanical hand. I encountered a couple of problems, especially with the strings and the lengths, so make sure to not make it permanent until you test it out. I didn't find many uses for it, but I'm sure there must be something. If any of you guys paint it, please post it down in the comments so I can improve it. As always, thank you for reading.
Participated in the
Cardboard Speed Challenge