For the Mister's thirtieth I made him a cake in the shape of the big 30. I was actually quite nervous about how this would turn out and I am presently surprised that it worked out so well. I personally find creating any number that's curved to be quite tricky. That being said here's the easiest way that I found to make a 30 shaped cake.
I used two round cake pans, a 10 inch and a 6 inch cake pan. After baking the cakes and letting them set, I carefully turned them out on to cutting boards. Any cake recipe will do here's the one I used.
To create the zero, I simply used a clean 6 inch cake pan and centered it over the baked 10 inch cake. Using even and firm pressure I cut out the center using the 6 inch cake pan as a cookie cutter. I simply elongated the circle to create an oval zero shape.
The 3 shape was a little trickier. I used the center cut out from the zero (aka the 10 inch cake pan), as well as the baked 6 inch cake for each lobe of the 3. I cut a straight piece off the bottom of one of my cakes so that it would lay flat on top of the other cake, and removed the center portion with a knife.
I repeated this process for the second lobe, rotating the bottom cake to form the bottom lobe. And there you have it a perfectly shaped 3. All that was left to do was frost the cake and add enough candles to set off the fire alarm.
Other options I saw included baking a rectangular cake and freehand or using a circular pan or glass as a template create the shape of a 3.