CAD style program control

I need to build a simple CAD program that allows people to drag lines from from one object to another on the screen and tell them how far the objects are apart based on whatever measurement I'm using. Also, I need for them to be able to click objects and have radius circles appear around the object on the screen of various sizes. Does anyone know of a control for C# that would help with that? Thanks.

You would have to write it yourself. It should be pretty simple, especially your first question, you just need to keep track of clicks and use pixels as a measuring stick (i.e., 1 pixel = N inches or whatever).