Using the Build Direction Tool to Orient the Part
Geometry extraction attempts to determine the part’s likely orientation on the build platform. The part’s orientation affects machine feasibility, build time, and material use.
By default, aPriori generally chooses an orientation that minimizes the volume of required support structures (see Additional Direct Costs—Support Structures, Support Structures for Metal Sintering or Support Structures for Resin Curing). In any case in which you do not want to use the default orientation, you can specify an orientation explicitly.
Follow these steps to specify the part’s orientation:
1 Select the Build Direction tool 
from the Viewer toolbar. The direction that is currently upwards for the oriented part is indicated by an amber arrow.
from the Viewer toolbar. The direction that is currently upwards for the oriented part is indicated by an amber arrow.
2 Choose a flat or cylindrical surface that is normal to the direction you want to be upwards for the oriented part: in the Viewer, hover over a surface that is normal to the direction you want to be upwards. The surface is highlighted, and a yellow arrow appears indicating the normal. Click to designate the normal as upwards.
You can also hover over the bounding box midlines—in blue above—in order to highlight directions; and you can click to select them. In addition, you can click the Advanced button in the Build Direction dialog, and specify upwards based on azimuth and zenith angles.
Note: Changing the build direction triggers recosting.
Note that the choice of part orientation determines which dimension of the part’s bounding box is the height dimension, which affects various feasibility and cost calculations.