3D-printed mold as casting mold: YouTuber makes plaster cast

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February 27, 2026 News 8912

3D-printed, single-use PLA molds enable direct plaster casting, as demonstrated with a bust.

Many casts from 3D-printed parts are made using silicone molds. Many people do this not only with metal, but also with plaster or chocolate. Denny from the YouTube channel “Shake the Future” shows a simpler version. He prints the mold from PLA and pours the plaster directly into it. The PLA mold is only intended for one cast, as shown in the example of a bust.

The method uses a negative mold, as in classic mold making. The difference: the negative comes from the 3D printer. Denny creates the negative mold with a resin slicer and saves it as an STL file. He then prepares the print in PrusaSlicer. He aligns the part so that as few supports as possible are needed inside. If supports are needed, they can be removed later, as long as you can easily access the inside.

After printing, Denny mixes the plaster and pours it into the PLA mold. He then waits about an hour for the plaster to set. At this point, the cast is still damp. He takes advantage of this: the residual moisture is heated in the microwave, softening the PLA. This allows him to cut open the mold with scissors and remove it from the plaster. The PLA mold breaks in the process, so the method is intended for a single cast.

One advantage is that because the plaster is not yet completely hard, the layer lines from 3D printing can be smoothed more easily, for example with a wet cloth. If you need several identical casts, silicone molds are usually a better option because they can be used more often.