The final step is to make the model compact by positioning the two groups as near to each other as possible, minimizing their combined bounding box. (A bounding box is the smallest imaginary box the model will fit into.) This will save space in the printing tray, and the print service will give us a better price. We don't want the parts to touch or intersect though, or else the printer will fuse the two parts together.

Placing the roof in position over the walls will make the smallest bounding box for this model. The design guidelines specify a minimum of 0.4 mm clearance between two parts to keep them separate. To be safe, let's move the roof 2 mm up and 2 mm forward toward the entrance door to keep it separate from the walls, as shown in the following screenshot: