Peaucellier linkage 4 

This mechanism has 2 degrees of freedom. The base of ordinary Peaucellier-Lipkin linkage (in white) can rotate around the vertical axis (in blue) thanks to the beige motor through gear drive (purple and white gears).
The orange motor controls motion of the pink crank through bevel gear drive (yellow and pink gears).
When the beige motor stops and the orange motor rotates, the yellow cone draws a straight line.
When the two motor rotate in opposite directions at the same speed, the yellow cone draws a circle.
By combination of various rotations of the two motors the yellow cone can draw any desired curve in the plane perpendicular to the vertical axis as shown in the last scene of the video. The drawing area is inside the pink circle.
A possible application: 3D printers.
Inventor files of this video:
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