Modelling a Dalek

Just started to modell a Dalek and I’ve come up against one of what im sure will be many problems. Making the main part of the body is easy but I’m having trouble with the half spheres that come out al over the body. The main trouble im having is putting them in the middle of the faces and matching up to angles they have to be on with the angle that the faces is on. This a a problem ive come up agaisnt with a few things, is there any way to do this easily so that the bottom of the half spheres meets flush with the face of the main body and is the same all of the way around the Dalek and up and down faces that are on leans?

While in edit mode select one of the face that you want the half sphere to be on.
Press shift-v to open the align view menu and choose to selected(top).
Now press shift-sand choose snap cursor to out of edit mode and add a sphere, delete the half you dont want.
Tab back to object mode select your main body object and shift-s snap cursor to selection, and then add an empty.
Select you halfsphere and add a array modifier, set the object name to your empty name and switch on object offset (switch off the other offsets).
Set quantity to the amount of faces around the body you have and then while looking down from above the body rotate the empty by 360 divided by body faces.