Dear Keith,
Thanks for considering Aspose.Slides.
Yes, you can create PPT and PPTX files on the fly from scratch or from existing ones.
Please see Aspose.Slides demo here.
http://www.aspose.com/demos/aspose.slides/index.html
To see the features provided by Aspose.Slides, please see Programmer’s Guide here
http://www.aspose.com/documentation/file-format-components/aspose.slides-for-.net-and-java/programmers-guide.html
However, PPTX functionalities are limited at present and will be enhanced with time.
Many Thanks and Kind Regards,
Shakeel Faiz
Support Engineer
Aspose Tyumen Team