I am new to CC and I'm hoping I can get some help here. I was asked to make a sandcastle wedding cake for a bride next month. Attached is the picture she sent me, except she wants a third tier on top. The staircase would start in the middle and has a few steps up to the left and the right, if that makes sense. Any tips on how to carve the staircase? I'm feeling a little overwhelmed by it.

Full thin circle on the bottom then three thin circles each with bits cut out to arrange into the stair is what I would do. Buttercream it all then it loooks to me like you just need to cover the whole thing with a bunch of sand while the buttercream is still soft.

i find nilla wafers in the food processor make good sand. 

Oh thank you! I didn't even think of doing it that way, but that would be so easy!

just carve...mark depth with toothpicks.