I baked 5 6" rounds. Split them. then built 3 mini cakes. Each had 3 half layers, cake-SMBC-cake-Ganache-cake-SMBC. Then I stacked the three mini cakes. Each with its own cake board. Each layer had four straws to support the next layer. then I buttercreamed the entire stack. I should note that there is a significant internal structure as well. The cake board is reinforced with a sheet of masonite underneath. Then with holes drilled in the center I screwed a metal flange under the base. first is a 5inch long 1/2" diameter PVC pipe threaded into the base. then I added a threaded PVC coupler to the top of the 5 inch PVC pipe. The head is RKT built around the 5" pipe/coupler and then sculpted to the shape. I then frosted the head to get as smooth a surface as possible to then Fondant. Next, is the brim of the hat, I cut an 8" circle from the masonite board. Again drilled a 5/8" hole into the center of the board to have a tight fit on the center structure. If I were to make this cake again I would add another 1/2 to 3/4" to the size of the brim. I then threaded a 10" pvc pipe into the coupler. The brim is supported by the coupler which is wider than the pipe, therefore there is no downward pressure on the head.
I had an extra pipe I used to stack the three mini cakes and then crumb coat the whole thing. The very top of the hat (the sideways peak) is also RKT. The whole thing into the fridge for several hours until very firm.
To Fondant the hat I rolled out a sheet and then wrapped around the outside of the cake. Then I added a circle to the top and smoothed the seam.