Finding an object in a physical environment is difficult if the environment contains many objects, especially if it is large and dense. We propose a design space that describes and compares existing guidance techniques according to four dimensions: output modality, physicality, granularity and spatial information. Output modality can be visual, audio or tactile. Guidance information can be displayed using physical objects or virtual artifacts. Granularity indicates whether the technique serves to navigate towards the vicinity of the target or to precisely localize the target. Finally, spatial information is either exocentric or egocentric. This design space aims at providing an overview of the domain and helping designers and researchers to understand the key properties of these techniques. It also enables their comparison and the generation of new techniques by highlighting unexplored areas.