Autodesk Inventor supports import of ISO STEP product data files (.stp, .step) and can process them for making new projects (.ipj). As far as we known, you can create these projects only in Inventor, so no other software will help you here.
Convert ISO-10303 STEP product data to AutoDesk Inventor project.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert stp to ipj on Windows
Autodesk Inventor is 3D solid modeling and design tool used to design and simulation 3D digital prototypes.
Autodesk Inventor shares 2D data from the AutoCAD and 3D design data from other Autodesk's applications. Autodesk Inventor is available for Microsoft Windows.
Convert from stp file
to ipj file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.