The project needs further development to make it more robust but is still used in its rough form by my son. It is quite rough around the edges.
It was originally intended to use another project (air pencil https://hackaday.io/project/11662-airpencil) as the input device however that proved to not work very well.
My son tends to use the keyboard to drive the application rather than touchscreen as he finds he tends to smear his inputs on a touchscreen where on a keyboard, whilst it is slow, he is more accurate overall.
Currently I have stopped work on the project to get other things done but intend to finish it off at some point as it has proved useful.
Code is in GitHub https://github.com/jonkster/mathscribe If you want to use/borrow/hack it, be aware it has bugs and rough edges!