Creating a 3D Model with Tinkercad - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 137

Drag a Round Roof object to each end of the rectangle. Use the Zoom feature
to help you make sure the edges are touching. Even better, you can overlap the
Round Roof objects with the rectangle by a tiny amount to ensure that no gap ex-
ists between the parts. Figure 7.13 shows the outline of the Medallion so far, and
you can see that the parts slightly overlap.
Figure 7.13 Slight overlap.
Now I need to group these three objects so they will behave as a single object.
This not only makes it easier to drag the medallion around the screen, but it also
makes any changes in thickness, for example, apply to all three objects (rectangle
and two Round Roof objects) at the same time. To do this, drag a selection rect-
angle around all three objects and click the Group button indicated in Figure 7.14 .
Notice that the colors of all objects change to a single color.