Yes, he conceives buildings in the traditional sense—like the in-progress Museum Fort Vechten in Utrecht and the National Pavilion of the Kingdom of Bahrain. But many of Holtrop’s projects equally engage the principles of fine art, design, and more. With a recent series for Belgian limited-edition editors Maniera, Holtrop has branched out into furniture, creating unique and intricate shelves, a desk, and a mirrored room divider that manipulate artificial materials (MDF and paint) to conjure the natural world—namely, the patterns and textures of a particular collection of stones owned by 20th-century philosopher-sociologist, Roger Caillois.