Hello Everyone

I am new to fondant icing decoration though I have done 3-4 fondant cakes before and never experienced this..This time when I covered my cake with fondant icing and smoothed the top sides and edges of cake so there is no air inside it looked perfectly fine but after 6-7 hrs i could see my fondant icing hanging down at some place like something hangs down because of it's weight..I am not sure where I am getting this wrong please help me !! I am using MMF thank you for any help !!

This has happened to me too on occasion. It is probably because of the thickness of the fondant. With fondant, you don't have to go very thick. Not only does thick fondant become harder to work with, it is also a waste. A lot of people don't like eating it, so it's purpose is, most of the time, purely aesthetic. Try rolling your fondant thinner next time and see how that works. I've read in multiple sources (Wilton for starters) to roll it 1/4" thick, which to me is really thick to cover a cake. I'd see how an 1/8" works for you. 

Good luck!

It could be a number of things - too much buttercream under the fondant, too thick of fondant, or your fondant doesn't have enough powdered sugar in it if you made MMF. MMF tends to stretch a lot so it might be stretching off your cake. 

Try tweaking your recipe with a touch more powdered sugar, try rolling thinner, and try not putting a lot of buttercream on your cake. 

Just keep practicing, and you will get there!

Oh Might be the rolling is the problem cuz i could feel my fondant is too thick..I will take care of it from the next time..Thanks for the advice BTW the picture you can see in my avatar is the cake (Thomas cake - my third attempt with fondant) I made it at my son's 3rd Bday party & I happened to face this very problem and I finally covered it with green fondant loll...

Thank you so much "mfeagan" & "Urbangrl2007" for the tips and advice I will try to keep 'em in my mind for my next project..Have a great weekend !!

Your cake also might be settling, and as it settles it will lose a couple millimeters in height.  The excess fondant will have nowhere to go so it will sag and bulge.  I used to have this problem too until I came across this thread.  The first post explains how to prevent this, works like a charm!  http://cakecentral.com/t/633571/my-newest-trick 

Adorable Thomas cake btw!!

yep! Great cake. I love the idea!