Pictured are the sprites that I used to help me design this automaton. You may want to take some creative liberties with sketching out the sprite and constructing the machine, so these might help you with that. Alternatively, you could just look up "charizard sprite" and get a million different options to draw off of.

Supplies

Pasteboard

Many different lego bricks, nonspecific

2 Lego wings

2 Lego axles

1 Lego wheel

Lego gears

Rubber bands

Cardboard box, nonspecific dimensions

Crayons, colored pencils, or a preferred coloring tool

A good pair of scissors (must be able to cut cardboard)

Step 1: Sketches

Start off with drawing 7 pieces like the ones shown above on a pasteboard. If you use regular printer paper, then the automaton will be a lot less durable, so I strongly recommend you use pasteboard, which you an either create yourself by layering a bunch of papers or buy from staples. Like me, however, you probably have some of it sitting around your house. I’ve written which sketches are moving and thus the most important. I’ve separated the body and the tail, though both are static, to prevent later problems with construction.

Step 2: Coloring in the Sketch

Color in the above sketches. I used crayons, which I think looked just fine for the purpose, but you can feel free to use whatever you want. It doesn’t take a great set of art tools to sketch these pieces and color them in, but if you put more time into this step you will get a better-looking result.

Step 3: Cutting Out the Sketch

Cut out the colored pieces. Make sure you've colored them satisfactorily first, because it is significantly more difficult to color the pieces once they've been cut out. I’ve assembled them in this picture, but it’s not necessary to do so. Just make sure that they are proportional to each other. Generally, they should be about 7 inches tall and 8 inches wide when assembled like this, but if they aren't, you can just scale the cardboard box up or down.

Step 4: Topping Off the Design

By using the 4x4 donut block, you can have a piston sliding through that moves the kinetic parts while leaving the static parts alone. The static part is the base for the kinetic parts to move around. At either end of the top brick, I’ve connected loose hanging wings that are free to flop around. I found that it doesn't work well when the wings hit the studs of a lego brick, so I put a rounded block on the top which allowed the wings to move substantially more smoothly. When the piston pushes this brick up, the pivot is higher and so the wings go to a tighter angle with the vertical. On the front of this, attach the body of the Charizard to a block placed on top of the donut block (static) and place the wings and head on blocks attached to the wings (kinetic). I used tape for this purpose, though glue would probably work fine. The third image shows how it looks, although without the head attached.

Step 5: Piston Mechanism

This system converts motion from spinning the wheel into linear motion to push the piston. The wheel controls an axle that travels through a brick that connects with the rest of the design. To make it easier to push, I connected a longer thin axle with a rubber band to the line of bricks at the top, and it runs pretty smoothly this way. Notice that I constrained the axle's motion with a donut block and a lego covering half of it, because it wants to move in a full circle, and this can get choppy as there isn't any room for the end of the piston to move side to side. I will constrain this further as part of a later step.

Step 6: Spinning Feet

With the pictured system, make a wheel or gear that can rotate axle going through the middle of the frame. This axle should have a gear, or any other sort of wheel that won't fall off, at the end for the feet. The feet should be facing opposite each other, taped together at the center of the gear/wheel for a sort of cartoonish animation. Notice the revamped structure, you can frame this automaton any millions of ways. That’s why I didn’t describe a specific design for the frame, but I recommend using a thick, reinforced structure, which is used from this step on.

Step 7: Pulley System

Using lego wheels with the rubber outside removed, there is a gap along the edge of the wheel that allow you to fit a small rubber band around them. With the pictured system, you can transfer the rotational motion of the controlling wheel upwards so that it controls the feet as well. By using the lego blocks that have a hole in the middle for axles, you can transfer the rotational motion on the back side of the automaton, which makes it easier to set up, even though it is possible to do it on the front side.

Step 8: Cardboard Box Frame

Taking a cardboard box, cut out a circle of radius 2 in and a big box of width 8 in and height 6.5 in. If you have different dimensions from steps 1-3, then you should cut out whatever size you need. Cut out insets for the middle third of the bottom and the upper-middle quarter of both sides. The inset at the bottom is unnecessary if the box is wide enough to allow the automaton to fit without adjustment. What it helps for, however, is meaning that you can use pretty much any box you'd like with a few adjustments.

Step 9: Finished!

Place the automaton in the frame! It serves to allow you to control the Charizard from behind while letting the design rest on a table. Notice that it was only at this point that I finally added the tail. This is just because it got in the way of making the rest of the design. The wings flopping around while building is also frustrating, so you might want to hold off on adding any body parts to the design before you have finished the mechanism.