Mouse from Spirited Away Shader

Created a production blog on my own shader for my first assignment for Programming Shaders. I was required to choose one out of the three shaders that I have done and further explain my process.

In the end, I chose this shader for my assignment. It is mainly made out of simple shapes such as the circles and ovals.

Here is a screenshot on my rendered shader:

What did I do?
I did the fat mouse from Spirited Away. It was initially a huge baby but a witch casted a spell on him and turned him into a mouse temporarily.

Reference Picture 

How did I do it?
Combining basic shapes to form seamless unique shapes by overlapping them. I used quite a lot of circles to mask out certain areas. For the outline, I simply increase the sizes of the shapes and place them behind the original shapes. There are also little details on the mouse that resemble wrinkles. Those wrinkles are circles that were masked out by more circles. Everything except for the nose of the mouse is made out of circles. The nose is made out of an oval. The background is a gradient from blue to white but I personally do not think that it is visible enough. 

There are a total of 5 colours for this shader and 4 floats to create parameters for the mouse's nose for easy adjusting. 

What problems did I face?
The little details were quite a challenge. Initially, I tried using cresents to make the small details. However, I resort to using circle shapes and masks instead. Although it was tedious, it still works.

What improvements to be made?
If I had done more research, I would be able to add in more details to make the shapes more define. I will also try my best to soft-code my work in the future.

Screenshot on code:

 

Final Shader