Ok, here’s an idea. When one makes a sketch, one puts lines over lines. Every new line is a correction of the previous one. The last lines are the ones that make the definitive drawing. So what if your software would gradually erase early line automatically? That would be the first step towards better digital sketching. The next step would be to use machine learning to analyse the users corrections in lines and to correct them realtime while one makes a sketch. Have you considered experimenting with this kind of data driven sketch software?