Prop Challenge - Modeling focus
Sci-Fi Wall Console I challenge you to make this with techniques where you don't have to do an entire highpoly mesh. I'm talking about doing things like mesh decals.
Prop Challenge 2 - Modeling focus
Matryoshka doll Commonly known as Russian dolls. Texturing this is probably the harder part but I think you should try!
Substance Challenge - Material focus
Iceland Lava Moss Definitely look up other references of this material. Thanks 3DKyle for the recommendation!