The diagram you created earlier in this chapter is a bit boring for a young person to understand. Adults may be happy with cylinders, but they are not very childish. Your job is to amend this diagram into a more childish design.
Let's start with the aim of the diagram: Saving $ 0.50. Why not use a piggy bank for this part of the diagram? If you search Graffletopia using the word piggy bank, you should find a stencil called Cash Flow which does have a piggy bank symbol. Install this and amend your diagram using the piggy bank instead of the cylinder.
Given that the symbol of the piggy bank is well known in the western world as a savings symbol, you may even remove the word saving below the symbol.
You can now continue amending your diagram with various symbols and shapes from existing stencils on Graffletopia. For instance, you could use the cash register from the Cash Flow stencil to replace the food cylinder.
A word of caution before you go completely crazy...