Most stained glass framing is H or C profile - the glass fits inside the grooves and the pieces are soldered together but that profile can't be made in draw using sand. I hate to rain on a casting parade but I think it could be more easily fabbed from normal framing stock. All of the pieces in that design can be made from bar stock.
Thanks for the response guys. Sorry for not replying earlier but soon after I posted I caught the plague and have spent almost all of the last three days in bed.
As for the specifics of stained glass I couldn't tell you. It's my friend who is the stained glass artist not me. I'm only trying to supply what she asked for.
The problem with CNCing the design out is that there is detail that the pic I posted doesn't show. If you look closely at this picture you'll see a line, a half round, going through the hash tag like symbol.
Yes, we were planning on using pewter which is a very low melt metal, 450 degrees. In my early days of casting I melted pewter on a hot plate in an old pot. I do see your point about it cooling too fast in a sand casting flask though.
A plaster mold is a thought. I have a big fire pit. I wonder if I put the mold in the fire pit and heated it if that would help my chances of it filling?
I can see how casting it in pieces would be easier but I would worry about it not ending up round in the end. I'm also not sure what her other needs are. I'll have to talk to her more about it and see if that's a possibility.
T'were me, I think I'd try fabbing at least the perimeter out of a suitable diameter brass or copper tubing. Can be soldered to, patina'd, or even polished for a bit of shiny color "splash". The remaining interior pieces would most likely have to be fabricated out of the stained glass borders, as I see differences in dimensions.
The window in the Film the Thick shape that you referred to in your first post is actually the window frame. The Stained Glass is made up into panels that are set into the frame. The Glass isn't soldered to it. Most frames would have a channel cut into them for the glass, there are several different styles. It could be a u-Channel that the glass sits in. This would mean the frame would have to be made in such a way the it was assembled with the glass panels slipped in (modern vinyl windows use this method). Another method that may work best for casting would be to cast a Rabbit into the frame, and cast a matching trim piece that could be fastened into place to retain the backside of the glass panel (old school wooden windows use this method). Either way you would need to work in a bit of a gap between the edges of the glass panel and the frame (the Stained glass artist should understand this) because the glass and the metal frame will have different thermal expansion rates. (this is more apparent with Aluminum). With the Thin cross section the the Aluminum vs the length. You maybe further ahead to make the frame in 5 pieces. the outer circle, then each of the inner spokes. Then either screw, weld or rivet the pieces together. (if you were to cast the rivets from the same pour they would be nearly invisible once peened over. If you have to solder to it, you would be further ahead to do it in brass. It takes soft solder very well, and you could solder the sections together with a torch. Based on the movie clip the designs on the surface of the window (if your try to replicate it closely are pretty simple. A small fuller in the center and it tapers from the center to towards the glass. All of which is foundry friendly (most likely because the frame for the real window is cast Iron).
Just my $0.50 worth