Add element
Roll a section
Shift-click dots, turn on Section, or use Select through to pick a section. Twist by 360° for a full roll. A loose ball only stays on upside-down track while a curve presses it into the rails, as in a loop or corkscrew; the simulation will show if it falls.
Control point
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Nudge moves the selected points as seen from the camera; ▲ ▼ change height.