MRRF: 3D Printed Resin Molds


Visiting the Midwest RepRap Festival, you will, of course, find a ton of 3D printed baubles and trinkets. A slightly more interesting find at this year’s MRRF was a lot of resin cast parts from [Mark VanDiepenbos]. He’s the guy behind the RotoMAAK, a spinny, ‘this was in the movie Contact‘-like device designed for spin casting with resins. At the festival, he’s showing off his latest project, 3D printed resin molds.

With the right mold, anyone with 2-part resins can replicate dozens of identical parts in an hour. The only problem is you need a mold to cast the parts. You could print a plastic part and make a silicone mold to cast your part. The much more clever solution would be to print the mold directly and fill it with resin.

[Mark] printed the two-part rabbit mold seen above out of ABS, filled it with urethane resin, and chucked it into his RotoMAAK spin casting machine. Six minutes later the part popped right out, and the mold was ready to make another rabbit.

Video below.


  1. Matt Stultz says:

    That’s great and it’s nice to see a kit coming out. I made a rotocaster to demo at the 2012 Pittsburgh Mini Maker Faire and to use for the same purpose (small scale mass manufacturing from 3D printed prototypes). If you have access to a 3D printer to make a few small parts, my rotocaster can be built with hand tools for about $60.

  2. fartface says:

    I really wish someone could figure out how to make a filimant to do wax printing on a 3d printer to do lost wax casting of parts. IT would be uber cool if you could take a $300 printer and do metal casting in your own garage (Yes a forge is trivial to make)

  3. Aztraph says:

    happy happy happy

  4. moo says:

    Why not sand and buff out the molds to make much nicer casts.

  5. Eirinn says:

    This will only work for things that don’t have undercuts or need flexing to release. Also you’ll have to make damn sure that the ABS mould has a release agent in every single crevice.

    • Galane says:

      Urethane casting resins tend to stick to just about anything except for silicones and non-polar plastics like polyethylene and polypropylene. If the surface of silicone has become deteriorated and roughened a bit, urethane resins can manage to stick to it so well it cannot be removed. I’ve had a few molds where that’s happened, destroying the mold despite release agent.

  6. I’ve been doing similar things with printing molds for soft robots on Z-Corp printers.

    When I’ve needed to compensate for undercuts or fragile geometries, I’ve printed molds that generate further molds.

  7. Eric D says:

    This instructable looks simpler than his rotational casting machine–For-Under-150/

    • MaxxForce says:

      I don’t see the comparison. Simplier… yes, less effective…yes. The instructable one is human powered. The RotoMAAK is motor powered. Are you going to hand crank molds over and over again, or even for a few hours for the clear resins and a perfectly consistent speed?

      • Eric D says:

        Sure, but you could motorize this solution as well trivially. Depending on how inexpensive the RotoMAAK is and whether it’s open source or not, it may be worthwhile, but in terms of something makers may want to make, it’s good to know the different ways of going about it.

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