The principle of unity-in-variety has recently been shown to affect visual aesthetic appreciation of product designs. We investigated whether this principle can also account for tactile aesthetic appreciation of products. Design students rated nine car keys on unity, variety and aesthetic appreciation through tactile exploration only. Results revealed that unity and variety, while negatively correlated with each other, both positively influence aesthetic appreciation. This implies that there is an optimal balance between tactile unity and variety that is aesthetically preferred. These results replicate results found in the visual domain and provide evidence for unity-in-variety as a multisensory aesthetic design principle.