FreeCAD open source CAD software supports export to several exchange formats, including ISO-10303 STEP product data files (.stp, .step). You can download the program for free and export your .fcstd files.
Convert FreeCAD drawing to ISO-10303 STEP product data.
We found one software available in the database for this conversion.
Multiplatform software - convert fcstd to stp on any platform
An open source multiplatform 3D CAD/MCAD/CAx/CAE/PLM modeler
Convert from fcstd file format
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.