This tutorial shows a convergent modeling of a plaque.
Initial stl file can be downloaded from here:
https://grabcad.com/library/3d-scanne...
The turorial uses some polygon modeling features:
Cleanup Facet Body: 1:51
Decimate: 2:38
Close Notch: 4:50
-Fill Hole: 5:21
You can check some supported convergent modeling features:
Scale Body: 5:45
Unite: 6:56