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I've created a 3d model using OpenSCAD, and now need to convert that into various 2d technical drawings for use in a patent application. I tried using OpenSCAD's wireframe view, but that did not hide hidden lines, and in other ways just generally did not seem tailored to the purpose of creating high quality technical 2d drawings.

OpenSCAD can, however, export to various formats including STL, and I thought perhaps there is some technical drawing software that could import the STL and use that as a starting point to make the 2d drawings.

I looked into LibreCAD, but it apparently does not support importing 3d STL files, according to this. I also noticed DraftSight, but think that runs into the same problem, as I have read that it is 2d-only as well.

FreeCAD I installed and imported into it my STL. I am less familiar with it than with OpenSCAD, but read that it has the same issues that I have with OpenSCAD, namely in being good for modeling but not good for drafting 2d technical drawings.

Having tried these free options, I realize I may have to purchase one of the purchasable cad options: fusion360, autocad, solidworks, or catia, which I've read have some ability to generate 2d drawings. That, in addition to their 3d modeling ability, should ensure that I could start with my 3d STL in creating the drawings. But I don't want to purchase one just to find out that it's 2d technical drawing capabilities are just an afterthought, as appears to be the case with OpenSCAD and FreeCAD.

My question is: What are the best tools for creating 2d technical drawings, which have the ability to import 3d STL and create the 2d drawings based on that 3d model?

I would like to get better at creating high quality 2d technical drawings, so, especially after struggling and failing to get CAD software to produce drawings, I'd like one that is specific to the 2d technical drawing purpose. Is there any such tool that can import 3d STL and is also aimed at creating high quality technical 2d drawings? Open source is preferred, but proprietary would be tolerable.

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FreeCAD is the right tool for the job (if not the only one for free), you just need to invest your time to learn it.

It has a TechDraw workbench you can use to generate technical drawings of 3D models with dimensions and annotations.

On a side note STL is the wrong format for what you want to to, because it is a mesh based format and will loose all geometric properties your solid model caries. Stuff like trim surfaces, construction history, circles, center points, radius etx will be lost.

You should use a solid based format for exporting like STEP, which is open and widely accepted, and FreCAD can natively read and use for technical drawings.

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One can use native OpenSCAD features to create SVG files from which one can edit to meet one's requirements.

The process can be performed by using the created model, within the code that creates it, but also can be applied to imported STL files.

projection() is the feature within OpenSCAD. Rotate/translate/scale/etc. the model as desired, perform the projection() feature and the results may be of use. Images below from the linked reference site.

projection example 01

The image below represents the cut = true parameter for the feature. Only points at z = 0 are used to create the drawing.

projection example cut = true

Alternatively, cut = false provides a "shadow" aspect of the projection:

projection example cut = false

As noted, one can rotate the model for variations of results:

projection example rotation

projection example rotation 02

Performing a preview (F5) creates a 1 mm thick 3D object, render (F6) creates an exportable 2D image.

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