Catia is my CAD of choice for most things, mostly because it’s what I know best. It however doesn’t have great support for STL files. We’ll be using FreeCAD to convert them to STEP files which Catia supports well. First we want to open our STL file with FreeCAD.
The entire process is pretty straight forward. We load the file into FreeCAD, create shape from mesh, and finally convert mesh to solid.
I just use the default value of 1 for the popup.
Finally we export the final shape to a STEP file. Catia can load the new STEP files without issues and let you start modifying them.