Modular 3D Printed Mold Making

I'm currently participating in the inaugural run of the Digital Fabrication Residency, which is a really cool virtual residency. This instructable covers a workflow from 3D printing to mold making to create an interlocking modular sculpture. It was my first time designing a form to be 3D printed.

Here is more information about the residency:

The Digital Fabrication Residency is a hands-on online intensive incubator for visual artists, designers and creatives with the desire to incorporate digital fabrication into their work to achieve highly specialized production for individual projects and public art commissions. The residency utilizes online collaborative tools to enable learning, consultation and idea development catered to the individual project needs of participants. This is an opportunity for artists, designers and creatives to engage in expanding their knowledge of digital tools, learn resources, exclusive workflows, and directly connect with other professionals in curatorial fields, related organizations, fabrication specialists, and innovators in 'making'.

The Digital Fabrication Residency helps visual artists, designers and creatives reach real-world results with feasible workflows that will enhance not only the physical output of creativity but also gain a competitive edge with project visualization tools for future RFP's and professional opportunities that represent professional level presentation in today's art and design fields.

As my first 3D printing design, I worked in SketchUp, which is a free program that is a great starting point. My goal was to create a modular form that could be replicated and interconnect. I was thinking about vertebrae and came up with a hexagonal shape with interlocking paws, somewhat inspired by barrel of monkeys. I started with a hexagon, added curved shapes on each corner, and then modified the lines to give it a more organic feel.

I tested to see if the arms would interlock when multiplied, making sure to leave a bit of extra space. The organic polygon was then extruded in SketchUp and finally 3D printed. I estimated the depth of extrusion because I wanted the forms to be able to snugly interlock and have the potential to stand vertically, creating a sort of 3 dimensional textile.

This type of mold is called a Dump Mold, and it was created using Smooth-On's Oomoo30. The 3D printed shape was hot glued to a piece of foamcore and then shallow foamcore walls were hot glued to the base. This creates a leak-proof box to pour the Oomoo rubber into. Once the two Oomoo components are mixed together, the rubber is poured into the foamcore box above the height of the 3D printed object. The rubber will set in seven hours. Any rubber that has crept under the form can be trimmed back with a sharp blade.

To make multiples, the mold was filled with SmoothCast325, which is dyeable. Like the rubber, this comes in two parts that are mixed together to start a chemical reaction. Dye may be added to add color to the resin. Once the resin is ready, it is poured into the rubber mold. The cast resin can be popped out while it is partially set (still malleable) and allowed to fully set outside the mold while a new form is cast.

Once the pieces were set, they interlocked beautifully! I'm still experimenting with the amount of dye and hanging them vertically. Backlit translucence creates a cool effect.