Sound symbolism is the process by which speakers link phonetic features with meanings non-arbitrarily. For instance, speakers across languages associate non-words with rounded vowels, like bouba, with round shapes, and non-words without rounded vowels, like kiki, with spiky shapes. Researchers have posited that this link results from a cognitive association between sounds and visual or proprioceptive cues made in their production (e.g. sounds of rounded vowels cue the image of rounded lips, which is mapped to rounded shapes). However, non-words used in previous studies differ from one another along multiple phonetic dimensions, some showing no clear iconic mapping to shape. This study teases apart these features, finding that vowel backness, consonant voicing, and consonant place of articulation each elicit a sound symbolic effect, which is amplified when these dimensions are combined. This investigation also probes object properties that can be involved in sound symbolic association, bringing the "bouba-kiki" paradigm, typically involving the use of abstract shapes, into the realm of real-world objects. To shed light on ways that sound symbolism may operate in natural language, this study suggests that future research in this paradigm would benefit from consideration of both more detailed phonetic correlates and more refined object properties.