Make a rabbet at any transition point from flat to round or hollow.
Make a rabbet to guide any round. Again, the arrises of the rabbet should approximate the angle of the finished profile. In this case they are at 45 degrees. (Why does this rabbet not fall upon the finished profile when Monday's did?)
Make a chamfer for each instance you will be using a hollow. The edges of the chamfer shall approximate the angle of the finished profile.
Knock of the corners with the appropriately sized hollow or round.
If this is getting repetitive it's time to stop reading, buy a pair or two at a local garage sale, and make a picture frame to match the one in your living room. Then send a picture.