Ah so for that, Solidworks has a cool tool that allows you to take the face of a 3d model and flatten it into a surface model. It's the flatten tool, and from there, I export the newly flattened surface model into a dxf and open in autocad (inkcape works the same, I just use autocad since I have a student license anyways).
Here's an example using a duct piece:
At the bottom there's a slit running down the length of the piece, this simulates where you would glue it after molding.
View attachment 166902
Next you select the "Flatten" feature, it's located under the surface category of the "insert" tab. To use the flatten feature you just select the faces you want (highlighted in blue) and the vertex for where you want the unfolding to begin (which is why you make the slit in the model, it breaks the continuity of the part and allows for it to be unfolded).
View attachment 166903
And from there you are left with an unrolled version of the 3D part. Next you just have to right click the part and hit export to dwg/dxf (doesn't matter which since both autocad and inkscape use either). The great thing about this is the geometry will be exactly how you want it and you know exactly how it will fold up.