I have looked at these videos to analyse the quality of the animations that are found in professional stop motion animations as well as the character design. In this animation (Morph) both characters are of a simple yet bold design. They use bright distinctive colours, which help the target audience (young children/toddlers) familiarize themselves with the characters. They also have a very memorable and instantly recognisable shape. The doll's limbs are long but not to thin, I also expect that the plaster-cine is modelled around some kind of thick but bendable wire to keep the models in a fixed and stable position when shooting an animation.  Maybe pipe cleaners?

A quick guide to stop motion...........

Once again in this stop motion the characters are thickly build to prevent droop and bending during shooting. Their colours are also distinctive and bold. The eyes seem to be set in sockets to make adjustments easier and the limbs are short and robust to help support the weight of the body. 

This animation is done completely from plaster-cine on a white board background. The animator has taken inspiration from Alien concept artist and painter H.R Giger. The sculpting skill is particularly impressive and becomes very inter-cut and complex at some points in the film. The animations are also very smooth and rhythmic and really produce an emotional response from the viewer. This work is also a very good example of an excellent use of materials and how they can be use to communicate a visual language through motion.