I want to construct a macro that will bring up the Solidworks Save As Box allowing the user to define a name and location for a file. I want to restrict the file type to .step only.
Try using the combination of API + your own Save as Form (instead of SolidWorks save as box) to insert changing data (e.g. Name = "H:\Assem1.SLDPRT"):
bool= swApp.SetUserPreferenceIntegerValue(swUserPreferenceIntegerValue_e.swStepAP, 214)
bool= IModelDocExtension.SaveAs(Name, Version, Options, ExportData, Errors, Warnings)
Check the macro by Simon Turner here: Re: Save As * Marcro
Change the extension from STL to STEP
Retrieving data ...