Many very poor Mexicans cannot afford the materials to create their art, so they scavenge in the dumps and junkyards to come up with the materials they can use. The paper people examples on another page also show the ingenuity of these people.

This is an old truck tire that has been cut and painted to depict some kind of fish. It is used as a hanging planter.
Here is a tiny helicopter made from junk. It uses a sparkplug as the body of the craft.
This little vehicle also uses a sparkplug for it's body. I buy this sort of thing to help support the poor people who make it. They are doing this instead of begging and I appreciate that.