The easiest way how to convert SCAD models to STL format for 3D printing, would be to download OpenSCAD software and simply export your .scad as .stl file. The program is available for free and for many platforms so give it a try.
Convert OpenSCAD CAD model to Stereolithography CAD file.
We found one software available in the database for this conversion.
Multiplatform software - convert scad to stl on any platform
A software for making solid 3D CAD objects
Convert from scad 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.