Empty mould as much as possible?


Given a simple solid, I have the corresponding mould (BooleanSplit of that solid out from a bigger box).
I will be 3D printing this mould, so saving time and plastic is key to me, in order to get something similar to the mould in this video https://youtu.be/bBbOUDDJv4Q?t=402 where the mould is basically empty inside.

I am attaching a simplified version of my mould, any idea on how to “remove unnecessary parts of the mould”?

Mould.3dm (4.6 MB)

Thank you

Hi David - the tool to use is Shell, at say .5 thickness, removing the top and bottom faces respectively. Rhino’s result is a little unclean here so there will be a bit of closing up to do.



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Thank you Pascal,

Any specific tutorial you would recommend on how to get it back closed? I have been successful until now closing surfaces, but have no idea how to proceed. I want this type of mould so bad, it’s exactly what I needed.

Hi David - before messing with fixing this, can you tell me if the goal here is to have a faceted thing made by the mold or is it meant to be a smooth blobby thing? My guess is smooth will shell more cleanly, and if that is what you really want here, let’s work on getting that done.


The molds will be used for the use case in the video from the first post: I will 3D print and sand them, to apply later carbon fiber between those two molds. The inside “cylinder” inside is the only part I care about. Removing/Shelling the inside part of the molds is just for making the 3D print feasible.

Not sure if this answers your question?

Hi David - the inside tube bit is faceted -

My question is, is this faceting required, or is it a smooth tube surface, in theory, or ideally? Because if it is meant to be smooth, then we should make it that way and the shelling part will (I predict) work out better as well.


Oh, I understand now.

I have been working on a 3D model that I purchased for this project, but haven’t modified this part, it is how it was originally modelled. Ideally would be great that it’s really smooth, because it would also save me time sanding it later on. Any help on that other path is really appreciate, as I’m learning anyways.

Hi David - this is a bit quick and dirty but see if is is close enough to what you want - if so, I’ll help you get there.

MoldHalf.3dm (314.5 KB)


That is perfect! It would be great to learn and apply the same to other moulds slightly more complex than this one.

Ok - so, I quickly extracted some curves from the already split part - to do this a little more correctly, I’d rather work with the full round part then split the result for making the mold - so, can you post or send me via PM, the thing you are starting with?


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