Convert from STL to STP?

I want to modify some of the parts, but I don’t know SCAD. I tried to convert the STL files to STP files, so I can use a range of software that I am familiar with. I followed the procedure described here, using FreeCAD:
https://grabcad.com/tutorials/how-to-convert-stl-to-step-using-freecad
The process appears to work, but trying to use the result reveals it is still only a shell. I believe the issue is with FreeCAD’s import of the STL files. It show this message:
Coin info in MeshRenderer(): GL_ARB_vertex_buffer_object extension not supported

and as a result the conversion fails because of many geometry errors.
Has anyone created solid models from the Openflex project STLs?
Pete.

Fusion 360 allows you to convert from STL to STP with relative ease. I’ve successfully managed to import and modify using this method.

Ryan

Hi Ryan,
THanks. I’ll check it out.
Pete.