Many online educational materials for sighted students such as presentation slides, PDF materials, MP4 videos, etc. are produced with Microsoft PowerPoint (PPT). In terms of non-technical contents, accessible PPT contents can be produced in a certain level; however, as far as STEM contents are concerned, there is still a serious difficulty. Our new add-on for PPT allows users to make efficiently/easily PPT STEM contents accessible. By making use of it, alt text/aloud reading by a TTS voice can be added to any technical part such as mathematical expressions included in PPT slides. An accessible MP4 video for STEM education also can be produced efficiently. By making use of multilingual support in Infty software, this add-on has been recently improved so that users can use it for PPT contents in various local languages other than Japanese or English.