recycling is used to rough the bottom circle & amoeba is a mean of machine for smoothing paper ->  sandpaper is a tool for smoothing the surface objects  an travel roof a goggles from steel & a lung is a mean of preposition ->  the wooden prototype is a kind of object  sandpaper is a tool for smoothing the surface objects & the wooden prototype is a kind of object ->  sandpaper can be used to smooth the surface of the wooden prototype  sandpaper can be used to smooth the surface of the wooden prototype & the centimeter circle a machine to rough the bottom of the wooden flower -> the engineer can use sandpaper to smooth the surface of the wooden prototype