slicer output to S3g

Hi folks new to 3d printing with an old makerbot replicator I bought. Wooden frame put together as a kit and not used many years ago. I have had success but a few questions about file format. Currently running from Makerware slicer but very slow on bigger models. I have tried another slicer...Cura...but can't find a way to put s3g onto the sg card so I can print. Looking at gcode to s3g conversion but no luck so far. Any ideas...apart from buying a more up to date printer which I will do as soon as I can. Would updating the old firmware be a viable option? Hope someone can help as I am a visual artist really excited about this new technique.