I frosted a cake in buttercream and put some buttercream stars on it with sugar pearls in the middle of each star. A while later the buttercream was bulging. What caused this?
Were the stars buldging or the cake? Where on the cake? Was it a ring around the sides where the two layers meet?
If so were the layers level? Did you put filling in between the layers? Did you use a dam around the lower layer to hold the filling in?
Sounds like you didn't use a dam OR it wasn't thick enough. Thicken b'cream icing by adding more pwdr sugar OR use fondant - make a thick rope - about 1" thick and lay that on the edge of the lower tier. Now put filling inside that, & place the top layer. Some peoiple say you need to let the cake 'settle' at least an hour but when one works a busy shop ther4 is no time for that. Just gently but firmly push down on the top layer some. If any buldging is to happen it shoulde do it now. If there is icing, just smooth it around the cake and proceed.