I could really use some help. I'm a hobby baker and I've been trying to improve my skills. Over the weekend I did a 3D cake. Standing Spongebob. I thought I had done a really good job supporting him. I used 2 1" dowels as the legs with a 1/2" plywood base the same size as the cake. 8"×4". He was 6 layers with 1/4" foam core between the second and third layer and 4th and 5th layer. 6 1/4" dowels in each layer. I covered in Gamache before the fondant. It was a dense dairy and egg free sponge with icing made with butter flavor Crisco. It was about 70 and a litthe humid. From the time I left my house until I got to the party he collapsed. The layers seemed to just crumbled and he broke in half. Any suggestions as to what went wrong and how to prevent it in the future?

It's hard to say without seeing a picture of the fallen cake... maybe it was too tall? Did you run dowels all the through the layers?