Yes! Yes! Cardboard is a perfect material for making prototypes. Here I present you a four legged walker I am working on. Now step one is finished, it walks forward :) And I am happy to share it with you.

Step 1: Check This Out!

Step 2: You Will Need:

Cardboard
Arduino Board
Servo Motor x4
Battery ( I'm using a small powerbank )
wire and breadboard
Sticks
Glue gun
Thread
Garden wire

Step 3: Cardboard!

So I started with a cardboard piece 53 X 17 cm. The dimensions don't matter so much just keep the ratios. My breadboard is 6 X 17 cm, which will occupy the middle part, then 6 cm on the two sides, then 17.5 cm at the end. After drawing, I cut out 1 cm from the middle to separate the legs.

1 cm worked but it would have been more comfortable with 2 cm, just saying...

Bend the sides on a straight edge as shown on the picture, one up and one down.

Step 4: Motors!

Motors! Servo motors to be more precise, two go up and two under. The two upper motors, named LeftUp and RightUP, get glued just under the first "joint". Make sure they are moving freely between the legs. The motors will move 180 degrees, so the servos must be opposite to complete a full circle. The side you put your upper motors on will be the backside of the walker.

On the second pic (other prototype) you see the motors on the bottom side, named LeftDown and RightDown, just glued on the middle facing away from each other. These motors are glued opposite as well !! But they don't complete a full circle, just half !!

With this prototype, I'm using a small powerbank which didn't fit on the upper part, so I glued it on the bottom side, but you can put it elsewhere.

I'm using the glue gun to glue the motors on place.

Step 5: Sticks!

You will need two 11 cm long sticks. Wrap the garden wire around it and on one end make a loop ( pic 2 ).

Have this loop connecting to the arm of the servo ( pic 3 ), make sure both move freely.

The other end of the stick is just getting glued on the "joint".

I added the breadboard and the arduino board now, but you can also add it later.

Step 6: Threads!

We are on the down side now:

You will need two 30 cm long threads. Take the middle of the threads and knot it to the arm of the servo motor so you have both ends free and equally long.

Move the arms of the servos to 90 degrees (like the arrow in the second picture). On the second picture it's not really 90 degrees, don't mind that.

Then you need to bend the cardboard once more as shown. Glue the threads where you bent the cardboard, the threads must cross at the front legs.

Plus I reinforced this with a line of hot glue so this section doesn't move.

Step 7: Code!

#include <Servo.h>

Servo servo;        // create servo object to control a servo
Servo servo1;
Servo servo2;  
Servo servo3;

int pos = 0;               // variable to store the servo position
int pos1 = 0;
int pos2 = 0;
int pos3 = 0;

void setup() {

//Connect the motors to pins 11,13,5 and 9 and of course VCC and GND
  
  servo.attach(11);                       //  LeftDown 
  servo1.attach(13);                     // LeftUp
  servo2.attach(5);                      // RightUp
  servo3.attach(9);                      // RightDown

  delay(1000);
}

void loop() {

  for(pos1 = 0; pos1 <= 180; pos1++)     // LeftUp
 {                                                             // goes from 0 degrees to 180 degrees
    servo1.write(pos1);         
    delay(5);                 
  }
  for(pos2 =180; pos2 >= 0; pos2--)       // RightUp
  {                                                           // goes from 180 degrees to 0 degrees
    servo2.write(pos2);        
    delay(5);                  
  }
  for(pos3 = 180; pos3 >= 0; pos3--)     // RightDown
 {                                                           // goes from 180 degrees to 0 degrees
    servo3.write(pos3);        
    delay(5);                  
  }
  for(pos = 180; pos >= 0; pos--)         //  LeftDown 
  {                                                        // goes from 180 degrees to 0 degrees
    servo.write(pos);        
    delay(5);                  
  }
  for(pos1 = 180; pos1 >= 0; pos1--)    // LeftUp
 {                                                          // goes from 180 degrees to 0 degrees
    servo1.write(pos1);         
    delay(5);                  
  }  for(pos2 = 0; pos2 <= 180; pos2++)    // RightUp
  {                                                          // goes from 0 degrees to 180 degrees
    servo2.write(pos2);         
    delay(5);                 
  }
for(pos3 = 0; pos3 <= 180; pos3++)     // RightDown
 {                                                           // goes from 0 degrees to 180 degrees
    servo3.write(pos3);         
    delay(5);                 
  }
for(pos = 0; pos <= 180; pos++)          //  LeftDown 
  {                                                        // goes from 0 degrees to 180 degrees
    servo.write(pos);         
    delay(5);                  
  } 
  
}