I created a flat cylinder and added a depressed center and further depressions in the top face (via the push/pull tool). I then used the extrusion tool to create fillets around the bottom of each depression. I encountered two problems, which you can see in the linked 1-minute video.
In creating the fillet, I first made a rectangle with the rotated-rectangle tool. But when I attempted to extrude it, SU said that the surface was curved. I switched to wireframe display and saw that the rectangle had only three sides. I added the fourth side, and could then do the extrusion. Can anyone explain this problem to me?
When I did the extrusion, several faces were left unfilled at corners. I thought that this might have something to do with drawing scale, but the problem persisted when I redid the drawing in feet rather than inches. Would this be caused by too small a corner radius? (I had corners rounded to 1/2" radius, and used a 3/8" quarter-arc for the fillet. Or 6" and 4.5", in the up-scaled model.)