Diagram.NET is a free open-source diagramming tools written entirely in C#.
Put Diagram.NET WinForm Control into your form and, like Microsoft Visio®, the user can draw shapes and links. With some code you can control, change, add and delete these elements.
This repository is a prototype for a research project that uses Diagram.NET. You can compare two repositories to see the differences. You can find the details about the research project here: www.mdeforall.org.