Interesting idea - using your 3d printer as an injection molder....

3D Printing
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Interesting idea - using your 3d printer as an injection molder…
http://www.instructables.com/id/Use-Your-3D-Printer-As-An-Injection-Molder/step3/Make-the-Casting/

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And not sensitive to filament diameter, so DIY filament would be fine.

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I can imagine this opens up some new possibilities in part intricacy… having worked in a foundry (cast iron) this idea is inspiring to me. I wonder…