Rational Bezier Surface Tool
A tool to create and edit rational Bézier surfaces with "weights" for the control points.
Rational Bezier Surface Tool

Use the Rational Bezier Surface Tool to model smooth surfaces that can be scaled indefinitely, allowing for more natural and intricate surfaces.

You can find the Rational Bezier Surface Tool in the Draw menu, as well as in the Right Mouse Button context menu once a rational Bezier surface created/edited using this tool is selected.

Draw->Rational Bezier Surface will draw a default rational Bezier surface around the origin and put you into the editing tool for the newly drawn surface.

Selecting an existing rational Bezier surface drawn/edited with this tool and using Edit Rational Bezier Surface in the Right Mouse Button context menu will also activate the editing tool for the selected surface.

To change the weight of a non-end control point, hover the cursor over the control point you want to change the weight of so that it is highlighted in green, type the new weight you want for it, without moving the cursor away from the control point, and press enter or return to influence the shape of the surface.

The editing tool also allows you to select either one of the 16 control points or one of the 24 lines of the control grid and move them in order to manipulate the surface to be the way you want it to be.

Note that the effect of changing a weight is different from that of moving the control point.

Inferencing is available when the selected point is moved and so is inference locking along the axes using the Shift key. Hitting the Esc key during a move will reset the surface to be the way it was before the move started.

Also, shamelessly plugging a paid extension of mine, you can use Rational Bezier Surface Properties to modify the surface(s) further if required.