MAS400 3D evolutes
Enter an arbitrary parametric surface and see its 1FF, 2FF, Gaussian and mean curvature and its focal surfaces.
Quite slow to load tbh, Ive not entered this very efficiently but thats why I didnt use geogebra in the presentation.
Unhide the surfaces and marvel, unhide the points and drag the handle around to see the focus of your favourite point on the surface.