Best Source File Format (3ds, .obj and .fbx) to convert into STEP for Metal Casting?


for a client we have sourced some 3D models from Turbosquid and they usually come in these formats:
.3ds, .obj and .fbx

Which of these file formats would be best to be converted into a STEP file format?
The STEP files will be used by the manufacturer to create metal casted figures (think of Monopoly figures) out of them.

And can this process be done with Rhino 6?

Thanks for your feedback!

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I just checked and meshes do not seem to be able to export to STEP, which I think is a Nurbs based exporter, if your mold maker agrees you can make an STL. file that they can use from Rhino with any of the Turbosquid files, but since I know a lot of guys who model for Turbosquid do it for visual and not for real life printing you will need to check the meshes, a good thing to do is check them in Rhino using Check Objects (Type in command line) or to download Meshmixer (Which I think is still free,) and inspect the mesh there, it also fixes meshes well.

Thanks for your feedback, yes it seems that with the standard export settings this is not possible:
Will check with the manufacturer if they can process .STL instead.
Thanks again.

as the warning says, Step files don’t work with meshes, you have to “convert” meshes into nurbs first but that’s not as easy as it sounds. there are few tools to help in the process but generally it means remodel the object using the mesh as reference. is long, is tedious but is the best result.
Depending on the object you can try with Sub-d ( if the mesh is not too dense and made by evenly distributed quads) for more information you can search in this forum for “mesh to nurbs” or “reverse engineering” you will find some automatic tools/softwares out there but it doesn’t work too well.

Some of these models might be able to be converted to NURBS by using the Quadremesher > SubD > NURBS. Here is the more information about it: Rhino 7 Feature: QuadRemesh

The most straightforward thing would be just to 3D print the mesh files directly for casting instead of this reverse engineering rigamarole, the most difficult and least fun job in CAD land.

The biggest problem is going to be that files your client found somewhere like Turbosquid are NOT going to have been designed to be manufactured, and are probably utter garbage beyond repair.


Thank you for the new tips. We will explore the suggestions and in parallel talk to the manufacturer, the 3D print idea might be the best. Thanks again!