Plastic elements are permanently joined with a hand-held welding extruder. Today, plastic welding has a similar relevance in production as the welding of metals. The existing extruders do not have optimal ergonomic and functional properties. The aim of Tina Blau’s diploma thesis was to work these out and at the same time minimise the dimensions and weight of the tool with a well thought-out technical design, and to reflect these advantages in the formal design of the tool. A simple and understandable handling was the focus of the form and coloring and thus led to a clear sign function.