i want to make a small 3 tier cake
4,6,8 inches

its for my sons first birthday for about 40-55 people

making a cake with fondant ( with marshmallow fondant i am making)

top tier chocolate with strawberry butter cream and fondant
second teir funfetti with chocolate butter cream
bottom tier marble with vanilla butter cream

im going to fill it with those icings too and coat it

do i still need dowels with it ?
are the frosting okay

am i missing anything

I would still advise that you use dowels and boards beneath each cake for extra support, you cant ever have to much support.

and buttercream that crusts usually holds up really well under fondant so i wouldnt see a problem with that. as far as serving sizes go, im afraid i cant help you with that as i dont know myself.

but it sounds really cute!

i would say from experience don't put to much butter cream on, i did and it turned out lumpy and i used my smoother didn't help, when you put it between layers cover and let it set, some even put something on top of the cake to prevent side buldging. there is a chart on here or wilton that tell's you about how much fondant you need same for butter cream but i would make more hope this helps

I would venture to guess you need more cake.

6 and 8 gives 36 servngs, i dont know what a four gives... you might be ok. those are wedding sized servings http://www.wilton.com/cakes/making-cakes/baking-wedding-cake-2-inch-pans.cfm
a 10 and 8 would be 62. (i am assuming its ounds you are doing? squares give more servings)
xx

The serving will depend on how tall you make the tiers as well. I would say if you are making them 2" high, it parobably wont be enough cake. Have you though about maybe making some cupcakes as well?

Yes, you still need dowels and cake boards for support between the teirs. Your sizes will be ok if your layers are 3-4 inches tall. You will have enough cake that way. Your fillings are ok but make sure to make your dam out of some stiff icing and make it a thin filling. Less to squish out. I also recommend, after filling and crumbcoating with a thin crumbcoat, let your cakes settle in the fridge overnight and then fondant them in the morning. This will help them squish whatever will squish out and then you can smooth it before the fondant goes on.

Cat