I made this party toilet birthday cake for a longtime family friend that is a plumber. I used two pound cakes and one yellow cake mix combined. I used an oval pan for the bottom bowl then used the same pan to mold the seat and cover using pastillage. I used two small square pans for the base and rounded one. I used one larger square pan for the tank.
I was having flashback of some nightmare cakes that were wobbly so, to stabilize the cake I used double cardboard covered in fondant between the base and bowl/tank. Put dowels in the base then long dowels thru the tank and down thru the cardboard. I covered a small glass bowl with fondant and paced it in the cake. The party was at a bar, so once I delivered it, beer and a brownie went into the bowl. The sheet cake is chocolate. I put dowels in the sheet cake and a cardboard base to support the cake (believe me this is very important). HUGE HIT, lots of compliments, and life of the party.