CARL G. TORSTENSON   Born in 1948 in Uppsala. Now lives in Tuna, Alunda, 20 miles north from Uppsala.   A great part of my experience of working with different materials I have got during my 20 years as a stage designer, sculptor and set painter at Upsala Stadsteater. Since 1975 I have had around 40 exhibitions or more and also participated in different joint exhibitions. I have also made some official assignment for the municipality; sculptures in bronze, stone and concrete,glase, and wood. From the beginning I mostly painted in oil or watercoular. Now I work with every expression or material.             I usually work with projects on a theme, and I try to come into a process or dialogue with the material until the ideas are emptied out.