When your sketch-based 3D model has weird shapes, it’s usually due to sketch geometry issues (like open contours, overlapping lines, or non-planar curves) or incorrect 3D operation settings (e.g., wrong extrude distance or revolve axis).
Sketch errors confuse the 3D tool’s interpretation of the form—unclosed loops or stray lines can cause missing faces or jagged edges, while non-planar sketches (curves not on a flat surface) lead to distorted results. Incorrect settings, like extruding too far or using the wrong revolve axis, also warp the final shape.
Start by checking your sketch for unclosed lines or duplicates (most tools have a "check sketch" feature), then double-click the 3D operation to verify its parameters—this often fixes simple shape issues quickly.