A bottom layer of sawdust is dampened and then tamped down
brightly died sawdust is sprinkled onto stencils
The neat part about this is people from all faiths and backgrounds participate. Some scary looking guys with tattoos all over were working on really elaborate designs next to a group of youth group kids whose design simply said Peace. People work for hours together in the hot sun.
Then later that day, the processions walk over the Alfombras
and they are brushed away.