What you are doing with CADtools is huge!! I will study your webpage on this project. It looks very comprehensive.
Have you had any experience with Rhino? The interface is very easy to learn and use. I was making complex parts within minutes of first using it.
pg. 18, Rhino version 3, User’s Guide:
Rhino is a "command driven’ program. Actions are activated by commands. Commands are accessed by ‘typing’ the command at the prompt, through the ‘menus’, or the ‘toolbar’. The choice is yours and there is no preference for one method over another.
I really like this structure. Whichever way you choose a command, the command line responds, offers subcommands which relate to the main command, and allows you to enter data - like ‘.x’ for x constraint, or numerical data. There are several clear ways to find a command. And Rhino’s command line responds with comments on how the program is interpreting your inputs. I hope in your CADtools for Blender 2.5 you add a command line for clearly inputting values. Scaling, moving, mirroring, rotating commands all let you input precise data. The orient command is also very powerful.
For an inset function in Blender you could have a command box for inputting the distance by percent and one for inputting the distance by measured value. Or the user could click and drag the placement of the inset edges.
I am going to try Modo 401 to see how easy it is to model things precisely. I have seen some amazing work done with Modo. One of my favorite digital artists is Cristóbal Vila, and he is using Modo. His level of care and detail is fanatical!
Picasso said, ‘good artists copy, great artist steal.’
Open source projects should be stealing what works from other programs.