The Avengers Birthday Cake!

I have always been a soft-core, Marvel fan and since watching The Avengers by Marvel, you might say it has become an obsession. On my quest to have everyone I know become obsessed with the Avengers, I bought tickets for my mom, dad, brother, and myself to watch the movie in 3D.
Carrying my obsession over to the culinary arts, I made a cake for my brother's birthday featuring the heroic group.
The cake is an Asian styled cake, layered with vanilla chiffon, pandan agar and a taro filling. The entire cake is covered in whipped cream then drawn on with homemade piping gel.
Homemade piping gel is so worth it to make because you get exactly the color you'd like and you can flavor it with whatever essence you'd like. The only downside is using it after it has been stored; the gel congeals and when you try to break it up, it becomes lumpy and is very hard to pipe. One of my foodie cousins helped me smooth out the gel so that I could pipe it out; it was a painstaking process and I would have lost my head if she didn't help me.
I had found a photo online that I modified and used as a template. The piping gel transfer did not work very well for me but it did enough for me to retrace the picture. After that it was just a matter of precision and patience. Since smaller details were very hard to pipe on, I omitted the eyes and some minor lines.
I was nervous of the outcome but near the end I was quite proud of my accomplishment. And not only that, the cake was a hit amongst the guests and Tommy really liked it. Success!

Homemade Piping Gel  (about 1/2 cup)*

1/3 cup granulated sugar
1 Tbsp. cornstarch (cornflour)
2 tbsp lemon juice
1/2 cup water
Gel Food Coloring of choice (opt)

Whisk sugar and cornstarch (cornflour) in a small saucepan.
Gradually add juice and then the water. Make sure there are no lumps.
Stir over medium/high heat until mixture boils and thickens.
Color as desired.

Will last about a month or so in the ‘fridge but will need to be at room temperature or reheated until smooth.

For the opaque white gel, I used 2 tbsp skim milk and omitted the lemon juice (cause it will curdle the milk). I also added a pinch of white vanilla powder for flavor.

I doubled the recipe for the primary colors, which was WAAYY too much. I have left over gel...what to bake next?