To Advanced Level ((full)) - Rhino 3d - Any Version - Beginner Level

Use Zebra analysis. If the stripes break, you failed. Use MatchSrf (Curvature) to fix it.

Your curve lines aren't actually touching (Gap = 0.001mm). Use SetPt (Set Points) to align ends. Rhino 3d - Any Version - Beginner Level To Advanced Level

This separates pros from amateurs.

Try these advanced-level tutorials to improve your skills: Use Zebra analysis

Draw a floor plan using Line and Curve . Extrude it using ExtrudeCrv . Type _Properties to change colors. Rhino 3d - Any Version - Beginner Level To Advanced Level