Autodesk 123D Design To Unity

Just wondering if it’s possible to get a model that I make in Autodesk 123D Design to Unity? Would I need the .stl file to be imported into another modelling tool and export it as a file Unity knows?

Don’t know if this can help: Online 3D Model Converter

Autodesk makes a free FBX converter. Export it as a dxf file from the 123d design app, then add it as the source file in the FBX converter.