3D Print Concrete Molds




Introduction: 3D Print Concrete Molds

About: Slice Lab is a think tank specializing in innovative digital design. We conduct virtual experiments where sculpture, technology and the organic world all crash together to create something new. We strive to pu…

Going from a digital design to a concrete sculpture us a 3D printed mold.

Step 1: Materials

I used Quickcrete which is a cheap, fast and easy to premix. I have found this to be a good mix for simple geometry.

Step 2: Digital Design

The faceted design was intended to serve as a geometry that could allow for easy mold removal with only two halves. This was also an exercise for testing surface linear relief treatment. A perforated skirt is added to both the midpoint and max convex point of the shape as well as the opening lip.

After exporting the file, the model was printed on a desktop 3D using ABS plastic. Flipping one side for both connection points to sit flat on the bed allowed for an easy print orientation that would allow for consistent line work along the whole piece.

Step 3: Test Run

I next removed the loose ends on the inside surface. Using 6-32 machine screw bolts, I bolted both halves to see the alignments of all the holes. I did not treat any of this surface nor was it sanded as I wanted to be able to see the printed ridges in the outcome.

Step 4: Setup for the Pour

Once I was ready to get to the pour. I set up a space that allowed me free range of motion, was clean and organized. The process of the pouring concrete can be messy, fast paced and stressful if you are not set up well.

First, I took a rubber mat to be my work surface and set all my materials and tools around the perimeter all of which were in distance of reach. Using a petroleum jelly or Vaseline I coated the inside of the surface in attempt to have an easier mold release process. Finally I set up a sturdy stand using wood shims and leveled the surface for the pour.

Step 5: Pouring the Concrete

Once mixed at a 3 to 1 water to concrete ratio, the slurry was ready to pour. Filling the piece to the brim was pretty straight forward with the large opening. Even with such a straight forward geometry I found it important to shake and vibrate the piece enough to fully fill the volume and let the air bubbles out.

Once done, I cleaned up the area around the mold pan and made sure not to wash any major concrete dust covered objects in the sink - the concrete can ruin your plumbing if not disposed of properly.

Step 6: Mold Release

After 48 hours I began to remove the mold. Unfortunately the piece was too gripped around the concrete due to the ridges on the layered print. For this reason this mold had to be pried off the piece and ultimately destroyed.

Step 7: Final Piece

The piece continues to lose water while getting stronger after it is release from the mold. The surface line work turned out roughly how I thought though I was surprised to see how the line of connection also created a line on the piece. This could have been prevented with a more carefully glance at the 3D print file thickness at the edge. Thanks for reading and stay tuned for more Slice Lab Instructables.

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    4 Discussions


    2 years ago

    This is a great use of 3D printing. If you added another seam around the other axis, you could re-use the mold.

    Vapor smoothing would also probably help a lot, and you can do it if you're using ABS or ASA (or PLA using MEK instead of acetone if you're not in California). I've done it with acetone in a rice cooker with ASA and the results were really good.


    3 years ago

    for future molds would it be possible to make some sort of flexible liner, maybe silicone, that would fit inside the 3D printed mold so that the 3D mold would give you the rigidity you need and the liner could hold the detail you want on your sculpture and still be flexible enough to get it off at the end without destroying it like you had to with the rigid mold?


    Reply 2 years ago

    There are many mold release sprays on the market that would work. Some can be found on Amazon.

    DIY Hacks and How Tos

    This would make a great way to cast custom concrete statues.