Abstract: A drawing aid having a sandwich-like structure in which the middle layer is an interchangeable pattern insert. The insert is interchangeable with other inserts, each insert having a particular pattern. The interchangeability of the insert enables the drawing of different lines, shapes, letters, etc. using the same template housing. A particularly useful embodiment allows one to draw a line over the insert pattern, producing broken lines without lifting the drawing tool.

Abstract: A variable resistance device having a moveable globule of liquid metal, contained in a channel, and having contact on one side with a resistive surface and on another side with a conductive surface, the resistive surface and conductive surface isolated from each other. The globule is moved by pumping a fluid through the channel, using a bi-directional fluidic pump whose pumping action is caused by selectively heating an adsorbent material. Selective heating is accomplished with a resistive material, dissipating power and controlled electronically.