I have made several of them. I use the sports ball pan. Use a heavy cake recipe (like a pound cake) Make the handle and the spout a few days out - I use gumpaste. Do not make them too big, they won't look right. I also use 2 tooth pics in each piece to hold them into the cake - kind of form them off of one of the pans so they have the curve they will need to match the cake. (you don't have to leave them like that to dry, it will hold the roundness) turn them several times or put them in a dish with p/s to hold them so they don't loose their shape while drying.
Bake a pound cake type cake. After it is cool, cut the bottom off of one of the rounds so it will set flat. Save that piece, it is what you will use to make the lid of the teapot. Put the rounds together, and put that piece that you saved on the top (I use a glass to cut it to the right size for the lid) crumb coat and ice it. I use buttercream, some use fondant whatever you like.
I then attach the handle and spout making sure you dont get the toothpics in the part of the cake that is the filling you want it to be able to be in the cake itself so it will hold. I then put some kind of trim around those pieces so it cleans the edges up somewhat.
You can make a rose or use another piece of gumpaste for the handle on the lid. These are not hard to do at all if you have any other questions, just pm me and I will try to help you!
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=2539
I forgot to tell you that you can trim the teapot out with whatever you want - I like to use royal flowers that I have already made, but you can use about anything - you can even just "paint" them if you want to.
I put a link in the above post to one I have done -here it is again -
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=2539
Loucinda,
Beautiful teapot cake!
Do you use a board between the layers or dowel the cake in any way?
Thanks.
No, no board between the layers. If the cake is traveling, yes, I would dowel it. (you can see in that pic that one is NOT doweled - the board was way too thin!)
Make sure you put it on a nicer board than I did. (1/2" foamcore works very well) I was new at the cake stuff when I did that one! 
There are some really nice teapots in the gallery - I just do mine very simple.
If you have a little girl, just copy the shape of the handle and spout off of one of her play teapots!
Oh - and make sure you mold the "opening" of the spout - it makes it look more realistic. (where the tea would be poured out)
Or you could make the handles and spout out of chocolate.
Well, I just did one last weekend and it was my first. I was gonna free hand carve it but I did something else very clever.
First of all, the cake was only for about 8 or so people, so it wasn't that big. I baked up 2 6in cakes and cut them in half and filled them with buttercream. I stacked them together and shoved them into my pyrex glass bowl that was round and tall. Then refridgerated it til the morning. Then I ran a butter knife around the inside edge and it came right out into the shape of a teapot. I then crumb coated and layed fondant over it.
I made the handle, spout and flowers about a week in advance and the lid too. It was all MMF.
Covered it in luster dust and put it together and wala!!
Here is a picture of the finished product..I have to say for my first teapot, I was pretty proud!!
http://www.cakecentral.com/cake-photo_1471373.html
Hello
I also made a teapot recently using this tutorial
http://www.make-fabulous-cakes.com/teapot-cake.html
Mine turned out hideous though (no pic!) but my Mum loved it. 
Thanks Rhiannon, great tutorial!
Loucinda - the tutorial says to attach the handles and spout with toothpicks. I still plan to just 'glue' on the handles, but is the spout too heavy to 'glue'? Do you usually use toothpicks? I am making the spout out of a 50/50 mix of fondant/gumpaste.
Yes, you will need to use toothpics for the handle and spout - they are way to heavy for just gumglue to hold them. (I think even spagetti would not be strong enough) The important thing with the handles and spouts are where you are attaching them - MAKE SURE they are going into the cake and NOT the icing between the layers!
Great tips here on this thread!
Just wanted to offer another option. If it will be traveling, you may want to use the wondermold pan. I covered this one with MMF. I used a wooden dowel in the spout and also used white candy melts for extra security. The handle and topper were also held in place with white candy melts.
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1329615
I have never done one with fondant - I have better luck with the buttercream on that round surface.
Can you "cut" some triangles of the fondant out around the bottom? (make it to where the edges would meet pretty cleanly though)
I am sorry I am not much help on that part. 
I finally finished! Here it is! Thanks for all of your help Loucinda. It's definitely not the cleanest work I've ever done, but still pretty cute.
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1490369
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