Creating a 3D Model with Tinkercad - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 140

Figure 7.16 Change the smaller medallion to function as a hole.
Now all I need to do is “sink” the small medallion (hole) object into the solid larger
medallion. I'll sink it only 1mm because that's the thickness of the hole now. Fig-
ure 7.17 shows that the hole is now inside the larger medallion.