Draw 3D Conduit or Cable Tray
To draw conduits or cable trays in 3D, go to
Ribbon: 
Draw 3D Conduit or Cable Tray
Pulldown Menu:
You will be prompted to select which conduit or cable tray is to be drawn in 3D.
Select conduit or cable tray in system to draw in 3D:
The entire run of the selected conduit or cable tray will be drawn in 3D.
Related Options
Draw hangers in 3D: Sets whether hangers are drawn.
3D circle approximation: Sets the number of sides on polygons used to approximate circles in the 3D model.
Show background below conduit and cable tray: Sets whether entities below conduits and cable trays are visible.