The top pewter section was cast in place into a 'dovetailed' hole so that it was retained when set (there was also a dovetailed, ie conical, groove at the base of this hole). The set pewter does not stick to the wood but it is a fairly close fit so this leaves it secure.
I have also removed a pewter shape after casting and glued it back in but this is awkward and I think unnecessary! Naturally the pre-casting top wood section looks different before casting - so it was cylindrical in this case. After casting the whole top, wood and pewter, is re-machined (mostly with a sharp scraper and then sandpaper) to get the round top, which is then drilled and the 'finial' (separately made) fitted. FTR the metal remains hot for some time after casting.
The glued sheet (sanded before glueing) is simpler as a start I think!