You can take a glance at this assembling animation for Bittle.
Here's a more detailed hands-on tutorial on building Bittle from the kit.
You can finish the following parts then put them together in later chapters.
Neck x 1
Servo arm x 1
M2x8 sharp-end self-tapping screws x 2
Put the servo arm in the neck part like the figure below. The teeth of the servo arm should face upward.
Screw two M2x8 self-tapping screws beside both sides of the servo arm. Don't over tighten the screws.
Assembled neck x 1
Chasis x 1
Front and back plate x 2
Side shoulder x 2
Recognize the front and back side of the chassis. The location of the two large holes along the center track makes a difference. In our standard configuration, we define the holes to be shifted towards the tail. You can also find a small mark "A1" in the front of the chassis.
Push the back tip of the assembled neck into the slot of the chassis. Then press down the front hook until you hear a snap sound.
Insert the chassis into one of the side shoulders.
Insert the front or back plate into the side shoulder. There are three tenons on each side of the plate. Insert the two front tenons as one group for better alignment.
Insert both the front and back plates.
Plug the other side shoulder to complete the body. Again pay attention to the alignment of the tenons of the front and back plates.
It's a little hard to explain well with words. Please refer to the assembling instruction video at 3:23. It requires more skill than force. There's a forum post discussing installing springs with varies tools.
Lower leg piece x4
M2x8 self-tapping screw x 8
Assemble the right leg. Insert the servo into the window. Watch the tutorial video to see the correct direction to fold the wire. The notch on the internal edge is designed to let the wire go through. Use two M2x8 screws to fix the servo onto the lower leg.
The left leg is opposite to the right leg. However, the front and back legs are identical. So you should make two pairs of legs with opposite configuration.
Chin x 1
Skull x 1
P1S servo with short cable x 1
M2x8 self-tapping screw x 2
Put the servo in the chin as shown in the figure. Pay attention to the direction of the servo's wire. After that, install two M2x8 self-tapping screws.
Insert the skull into the chin so that it can rotate and bite on small gadgets. I recommend you apply some lubricant to the contact points between the skull and chin.
P1S servo with short cable x 4
M2x8 self-tapping screws x 8
Lower leg (assembled) x 4
Put the head, body, servos, and lower legs like the figure below. Insert the short servo wires through the servo slots on the side shoulders. Pay attention to the direction of the servos carefully and place them in the correct configuration.
You also need to insert the wire of the head servo into the body.
Put the short wire servos into the side shoulders after confirming all the components' directions. Pay attention to the directions of the shoulder servos’ output shaft. The long wires of the lower leg servos should be inserted into the opening between the shoulder servo and the shoulder window. Use two M2x8 self-tapping screws to fix each should servo.