Being as you don't have any previous experience with a 2d program, learning a 3d program shouldn't be too difficult.
I know that sounds counterintuitive but it isn't. Most people that I know, that learned how to draft on 2d software and became good at it, had a harder time going to a parametric 3d platform because the design process is backwards.
In a 2d program (KeyCreator, TurboCad, AutoCad)you draw shape to fit the dimensions you intend to end up with. In a 3d parametric program (solidworks, inventor)you draw the dimensions to fit the shape. In Autocad when you draw a line you assign the length and direction when it is placed on the screen and you can trim or otherwise transform it to make it look like the finished product. Simple shapes can be pretty easy but you need to have some drafting background inorder to create a coherent drawing of a complex part. With Inventor you can sketch in a rough shape and then apply dimensions and "constraints" to lock it into the finished shape. You can then create a three dimensional object to represent your part. The program can then create a 2 dimensional veiw of your "model".
A 3d program can be more difficult for a software novice to operate but it sounds like you have a pretty good computer background, whereas a 2d program is easier to maintain but can be difficult to produce something that will look profesional.
Bottom line, I think for your application a 2d package would be the most cost effective route, you are not using it enough to get set up with anything more complex. That being said, I think a 3d package would be better for you from a learning curve stand point and for future expansion. If I was you and all I ever wanted to do was exactly what you have told us, I would buy a decent 2d package with simple 3d capability (I would recommend AutoCad or KeyCreator), take a class on how to use it and be done.
![[2thumbsup]](/data/assets/smilies/2thumbsup.gif "[2thumbsup] [2thumbsup]")
