Children with sensory disorders either get too much stimulation or not enough. Understanding which of these sensory issues a child has is key to developing the right artistic therapy program for the child. Clay is an effective material to use for children with sensory disorders. Play Doh or soft modeling clay will work. The cool, soft texture is soothing for children who crave touch. Shaving cream and marshmallows also make effective, fun art therapy materials. Art projects that require hammering are effective for children with hypersensitivity, since it helps them to release energy in a creative context.
Drawing and painting projects are perfect for children who have trouble expressing themselves verbally, whether the child has a speech issue or is deaf and doesn't communicate well vocally. Drawing and painting allows these children to bring their feelings out visually, which improves their artistic ability as well as their communication skills. Other situations for drawing and painting could include children who may have repressed fears or memories they need to talk about. Drawing and painting is often a good way to get children to express themselves on their own terms.
The focus here should be more on colors and having fun, since many of your mentally handicapped children might have difficulty participating in more complex art projects. Collages featuring various colored shapes of paper or photos cut from magazines might be a good way to engage the mentally handicapped child. Finger-painting is another effective artistic endeavor, since it requires no real physical challenge but can stimulate the mind of a child with limited mental capacity.