This might help although it's not the same chalice.
I'd form the top 'cup' part from pastillage (let it dry over a former) until solid. The upright I'd cover a wooden dowel. And the bottom is just rounds of paste/pastillage....
If you break it down into these three sections, it's not so difficult.
I'd use royal icing to 'glue' the parts together (actually, I'd probably have the dowel go right through into the cake, for stability!)
I would probably use gumpaste for the chalice too. I would start by making a domed cupcake topper by drying it over a foam ball and the stem I would make a sausage and insert a cake dowel so I could push it down into the bottom of the cake so it didn't sink and to give it stability. i would allow everything to dry for a couple of days before joining together and building the based and applying the finer detail. Good luck :0)
Look at the chalice and break it down into little components. The base is different sized circles on top of one another, then a cylindrical shape stem, more circles and then the top, which could be moulded over a ball or something round that is the right size. Add your decorations around the rim of the cup and paint it all silver to bring it together. Use modelling paste or fondant strenghtened with tylose. If you are worried about the stem not being firm enough put a skewer, spaghetti, or some sort of support down the middle of it. Have fun.
is there a tutorial in Margaret Braun's book? She's the chalice master.