I remember walking up and down the aisles of the supermarket as a child and always stopping to buy a few boxes of gelatin mix with my Mom. She would allow me to choose the color/flavor I wanted, and when we got home I would help mix the gelatin in the hot water until it dissolved. Then she would pour the whole mixture into a glass dish and place it in the fridge. When it was done, it just looked like a slab of whatever color we made in a square shape. She would take a spoon and scoop some out, and it would fall into my bowl shapeless and wobbly.
As I got older and started to explore the city more, I noticed these beautiful readymade gelatin molds at the Mexican markets. I started with 4 colors, and the gelatin mold was perfect. Everyone enjoyed eating it. Older people were happy, little kids were asking for more, and I was just happy that it turned out right. Eventually, I would build gelatin molds of up to 9 or 10 colors, but it's always best to start out small, and once you know you can do it, go for the gusto.