both times I tried making topsy turvy cakes ended in disaster lol. I have yet to try them again. The first one I finished but as soon as I did and stepped back and just knew it was going down! And I was right.. The moment after I snapped a pic the bottom tier split. I popped off the top two and (thankfully it was a free cake for a friends bday) when I delivered the cake the top tier slid off the 2nd tier lol. It was nearly in tears at the time but now I find it funny! I was a beginner and I knew NOTHING about supports!
More recent disaster. A wedding cake (again for a family friend) when I stacked it I had cut the dowels too short which caused a split in the side of the cake. THANKFULLY it was a white cake and it was right through a damask pattern. The pattern and color of the inside of the cake matched so well it was nearly invisible. I dont think anyone ever noticed it but I was mortified all day because of it!