Double click on the polysurface to open attribute setting and assign it to Part by opening dropdown menu. At this moment, user can see this polysurface is defined as Part (color is beige) in model tree. Hold Shift and select all lines. Click Attribute, assign them to attribute Cold Runner and click OK to confirm the setting.
Click Melt Entrance in Model Tab and Studio will automatically search and assign melt entrance on top of runner system. With part, cold runner, melt entrance established for molding system, click Mesh tab to prepare mesh model.