Stanford Bunny Mesh Mods: Voronoi

We use Meshmixer a lot in the shop, and teach our students mesh-editing techniques using it. Despite Autodesk's endless cat-and-mouse game with this unsupported software, we find it still works well on both Windows and Mac, and it remains an indispensable part of our workflow.

We demonstrate several mesh modification techniques from import to fabrication. Our subject is the famous Stanford Bunny, which comes pre-loaded with Meshmixer as a non-watertight mesh. These techniques are detailed at newMediaWiki, our Open Education Resource.

Voronoi

This demonstration, voronoi, uses a mesh modification to create a 3D Voronoi model with a low polygon count, about 11K. You can find Voronoi expressions in objects such as the Water Cube from the 2008 Olympics, the CNC work of designer Marc Newson, or the sculpture of Anthony Gormley.

For others in the series, check out our Collection: Stanford Bunny Mesh Mods.

Printing

Resolution: There are three different poly resolutions available for this model: one at ~33K, one at ~460K, and an ultra-high one at over 1M. PrusaSlicer warns about slow processing over 1M, but we've never had a problem with it. Use whichever works best for your print size.

Size: The original bunny is a scan of a terra-cotta garden tschotchke that stands about 7.5 inches high. The model can fit full-size on an MK4 build plate. But you can print it larger on an XL or smaller anywhere, however you wish.

On the bed: We've supplied raw meshes from Meshmixer. In the voronoi mesh, the base is fairly lumpy. You should cut a sliver off the bottom. We used Cut to delete the first 0.02 inches of height from the model, which ensured dead flat adhesion.

Supports: The bunny is impossible to print without support. Our strategy is to use paint-on supports, using automatic painting at an angle of around 40 degrees. 

With that said, you'd be surprised how well the rounded shapes in the Voronoi model print support-free. The areas around the ear, chin, and tail — places that need support on other mesh mods — clearly needed treatment, but the interior did pretty well without it. So, after painting, we went back in and, looking from the Bottom view, used paint-on right-click to block any support that led to a structure inside the body. We had to accept one of these for the ear, but it was remarkable how little this model actually needed.

We use organic support to avoid body-to-body support at the ears, and we typically expand the first layer from the standard 3.5mm to double or triple that to assist with adhesion.

Other notes: It's a sculptural object, so layer height, infill, and whatnot are discretionary. But don't waste a lot of material on high-percentage infill: we use gyroid at 5% and it works well.

Licensing notes

Stanford's work apparently happened before the evolution of licensing schemas on the web: their requirements are described here under the Please acknowledge… heading. We've applied a CC-BY-NC License as what seems to be the closest match with their text.

We brought the original mesh into Meshmixer and performed a mesh modification to create a 3D Voronoi representation.