Archimedes trammel draws an ellipse if you fix the base and move the handle.
What happens if you fix the handle and move the base?
Drag point D to find out.
See the curve.

Archimedes Trammel has 2 sliders and 1 degree of freedom. This ”supertrammel” has 3 sliders and still has 1 degree of freedom. We made one out of wood and enjoyed playing with it.
You can play with this electronic reproduction.