You can use ASP. VB, C# applet, JAVA, C++, VB Net, ActiveX, ARX, Framework, Lisp, VBA or what ever is faster and easier to do.
In attached contains two documents the Ellipse Spec is the one you are going to work on
1. Draws Ellipse base on user input, user is able to preview the drawing and will be able to change the default values.
2. Made calculation of ellipse (length, angle)
3. Made user interface like attached EllipseVB05 program.
4. Login system (When user decides to download or save the drawing, she has to login, if she then she will be directed to pay page (paypal for this project).
5. Save drawing in two deferent option dxf and PDF, and allow user to download or print the any of two formats or both in actual size (full scale)
I will provide EllipseVB05 source code, login system and shopping card in php and free of errors and bugs, you would just need to intergrade them but we will not take any responsibly for any male functionalities.