Several techniques exist to automatically synthesize a 2D image resembling an input exemplar texture. Most of the approaches optimize a new image so that the color neighborhoods in the output closely match those in the input, across all scales. In this paper we revisit by-example texture synthesis in the context of additive manufacturing. Our goal is to generate not only colors, but also structure along output surfaces: given an exemplar indicating 'solid' and 'empty' pixels, we generate a similar pattern along the output surface. The core challenge is to guarantee that the pattern is not only fully connected, but also structurally sound.

To achieve this goal we propose a novel formulation for on-surface by-example texture synthesis that directly works in a voxel shell around the surface. It enables efficient local updates to the pattern, letting our structural optimizer perform changes that improve the overall rigidity of the pattern. We use this technique in an iterative scheme that jointly optimizes for appearance and structural soundness. We consider fabricability constraints and a user-provided description of a force profile that the object has to resist.

Our results fully exploit the capabilities of additive manufacturing by letting users design intricate structures along surfaces. The structures are complex, yet they resemble input exemplars, resulting in a modeling tool accessible to casual users.