An interaction device or technique is a combination of hardware and software elements that help users accomplish a single task, in this case, to create 3D sketches. When talking about specific interaction devices or techniques, it is important to consider the needs of the user. For 3D sketching, these needs change depending on the type of sketch the user wants to create. It is also important to consider the affordances that different interaction devices or techniques have, as they affect the way users utilize them. Affordances are an attribute of the tool that shows which features they offer to the user. A limitation of 3D freehand drawing is the difficulty to control the stroke using the shoulder or the elbow. There is also a category of user interfaces that use interaction devices and techniques to mimic the actions of modelling an object with clay.