I've seen a lot of designs for Thomas the Train since he's a pretty popular character for boy birthdays. One design element that tended to pop up a lot on cakes were tunnels. However, almost all of the cakes I saw never had a real tunnel and I knew I wanted a challenge. So when I got the a-okay to go with it, I was excited to begin.
I took a 2 liter pop bottle and cut it so I could use the middle part. Be aware that nowadays, there are some brands that have the 2 liters that concave towards the bottom...you'll want the one that is straight all the way to the bottom.
I took white gumpaste, rolled it out and placed it on top of the soda bottle. I let that harden for a few days so it could be strong enough to support the cake and not collapse on itself. The length of the tunnel worked perfectly for an 8" cake.
Then I proceeded to make the Thomas the Train fondant figure. I used this image to get an idea of how to make Thomas.
The day before the party, I got to work on the cake. This was a white almond cake that worked really well for this design since the texture was more firm and better support.
After putting some strawberry filling between the two layers, I started carving out the middle part where the tunnel would be (my friends happily enjoyed the cake portion from that!).
I actually decided to add more strawberry filling in the middle since I had some extra space from the tunnel. I normally wouldn't put this much because if you put too much filling in the middle, the cake will form a bulge between the layers and I get paranoid that will happen to me! But it was okay with this cake since I had the tunnel supporting it. If you do want a lot of filling, you have to make sure it's a filling that isn't soft and can hold up well under weight.
I then iced the cake.
And proceeded to cover it in fondant. This was actually really easy to cover since I was able to move the folds towards the tunnel and trim away the excess.
Fondant covered tier.
I then covered a 6" tier with the same blue fondant, placed it on top of the bottom tier and put a border and the name of the birthday boy on it.
Added an archway for both entrances of the tunnel. Btw, I thoroughly enjoyed pushing Thomas through the tunnel like a little kid when I was making this cake haha!
Some hills on the bottom tier.
A few days beforehand, I also made some stars and a big "2" to place on top of the cake.
I also partly covered a 14" cake board with green fondant and put "Happy Birthday" on it.
Added the cake to the board, placed the "2" and stars on top of the cake and it was finished.