I have handled a lot of spandrels and looked at them very closely. Good ones have remarkable definition which I have assumed is part of the casting not a finishing process. I notice that they are thin, and that the high relief sections are hollowed on the back suggesting either shrinkage or pouring off the excess metal as with slip casting in ceramics. They have always seemed rather too fine for sand castings, but they do seem to be poured into some sort of imprint mould. They are hand finished so show little evidence of the method. Now, however, I have a set of modern made castings which make me wonder. They exhibit the same hollowed back, but they have the risers and vents still in place. Can anybody explain how these were made and how it might differ from the real thing?