An assemblage piece of art using the prompt "sleepwalker" could depict a figure, perhaps made of found objects or repurposed materials, in the act of sleepwalking. The figure may be depicted with their eyes closed, arms outstretched, and a dazed expression on their face. The figure could be made to appear as if they are walking through a dream-like landscape, with various objects and elements arranged around them to create a sense of movement or disorientation. The scene may also include other symbolic or metaphorical elements, such as clocks or mirrors, to further convey the theme of sleepwalking. Overall, the piece would aim to evoke a sense of mystery and dream-like surrealism.