Create a surface inside four boundary curves or corners (Square)

Use Square to create a surface by blending inward from a combination of four free curves and/or corners.

What if...?

I can’t create a surface from my curves?

Make sure your curves intersect. If modifications to the boundary curves cause them to stop intersecting (while construction history is on), a small red and yellow arrow appears at that corner. Right mouse clicking on the arrow displays a bubble with an explanation of the problem.

See Make curves intersect.
The Square tool tests whether curves intersect within the Curve Fit Distance tolerance in Construction Options. To change the Curve Fit Distance option, choose Preferences > Construction Options .
You can’t create a surface inside boundary curves with sharp corners, CV multiplicity, or multi-knots. To remove multi-knots, turn on the Rebuild option for rail curves.

The resulting surface is too complex?

Turn on the Rebuild options for the curves used to create the surface.
Turn on the Explicit control option, then manually choose how many spans the surface may have and what degree it should be in the U and V directions.

I want to change a Square surface after I’ve worked on other objects?

Choose Object Edit > Query Edit and click the surface.