While MEL (Makeup & Effects Laboratory) was responsible for many aspects of the film, their biggest contribution was undoubtedly the Goombas. These creatures came to life through concept designs, sculpting and animatronic work, costume design, and some talented actors. See how it all came together in the pictures below.
Concept Artwork
Prototypes
Sculpts (Un-painted)
Sculpts (Painted)
Mechanical Workings
Costumes
Related Links:
SMB Archive's Interview with MEL (Makeup & Effects Laboratory)