The second in the Mirage series of Mecha designs. Also done with pencil crayon, this design was supposed to be a ground based mecha as opposed to aquatic or space.
Sand and debris from explosions. I've seen some mecha series use flexible armor to hide what they can't draw (like inner joint details) so as a personal rule, I try and use them only after I've worked out how the internals look and work and if they make sence.