There's a way to convert STL files to STEP files easily and on the cheap, but the more complex the file, the bigger the STEP file will be, because it'll be made up of loads of triangles.

So my advice is to use apps like MeshLab, which has a few tools for this kind of thing to reduce mesh complexty, and then bring the file into Blender to further reduce the complexity of the STL mesh.
Blender also has some tools for working with meshes and cutting down the polygon count a bit, like the modifier "Decimate" with this you can reduce the size of the STEP.

Here's how to convert STL models to STEP for free:

Import the into FreeCAD and use FreeCAD's internal procedures to convert the model to a CAD part, under the workbench Part and use the command "Shape from Part"
After that, save the model as a STEP file: that's the quickest way.

This way you'll be able to work in Moi3D using snaps and the geometry from the scanned model, but keep in mind that STL models are meant for 3D printing and usually have a ton of triangles, so the exported STEP file will be really heavy to handle.

Of course there are other methods too, but it all comes down to your experience with both the software and modeling itself.

Converting an STL file to STEP format with FreeCAD sometimes took a while.

So my advice is to use mesh modeling apps like Blender and try to make some elements with SubD, then export the model as OBJ, and then convert it in Moi3D using the SubD command.
But there are many methods, and skills you pick up over time.

Last thing; with FreeCAD, you can import STL models and use them as a reference to create the CAD model directly with its built-in tools.
But as I said, it requires experience and it's not the easiest CAD program to use.
Still, it's useful to have it, because sometimes you run into these issues with Moi3D not supporting meshes.

Below in the image you can see an STL file from a laser scan converted using the method I suggested.

Cheers

STL decimated in Blender


STL exported from Blender and converted with FreeCAD into a part CAD


STEP imported from FreeCAD export


STEP imported from FreeCAD export

Hi pafurijaz,

re:
> This way you'll be able to work in Moi3D using snaps and the geometry from the scanned
> model, but keep in mind that STL models are meant for 3D printing and usually have a ton
> of triangles, so the exported STEP file will be really heavy to handle.

There are more problems with this method than just getting really heavy.

It's just fundamentally not the type of data that CAD programs are designed to work with.

No spheres, cylinders, or actual curved objects of any type, just a big pile of trimmed planes.

Usually it isn't a useful result.

- Michael

This saga isn't over for me yet

I tried reduction in Meshlab but it hangs around the 98% point for the obj file

I did get a 7.3GB subD file from the Alibre IGS in MOI exported as an OBJ file, a testament to MOIs stability

Does anyone know of a Utility for turning a polyline DXF into an OBJ file?

Edit: I'm better off turning an STL into an OBJ file aren't I, duh.