3D Drafting Software
3d Drafting Software comes in many programs and price levels nowadays. All the way from free packages, such as the basic version of Google Sketchup to high priced seats of Catia and a hundred titles in between. The worst thing with 3D is, everyone promotes their own file formats. Quite often you cant open 3D work done on one system so that you can modify it on your own system. It's a bit like the days of the industrial revolution in the mid 1800's when on factory made a nut and another made a bolt and you had no guarantee that they would ever fit together.
Fortunately there is some degree of standardization to allow at least completed 3d models to be imported into various other software programs. Most 3D drafting software will export to IGES and SAT formats which can be read with a variety of drafting and CNC machining packages. The only problems is, IGES and SAT formats are just "dumb solids". Anyone opening those files cant modify them in the same way they were created. They are pretty much only useful for the presentation and manufacturing of the finished product.
While many drafting softare packages have their own proprietary file formats, the way that they put their 3D models together is very similiar. Once you know how use one 3D package, its a safe bet that it wont take you long to get used to using another. The names of the functions might be different, but the functions of the icons you press you be pretty much the same. All 3D drafting packages require you to select planes and sketch on them. They all extrude or revolve models from those sketches and have features that allow you to add fillets and holes among other things.
One of the most important features that 3D software can have is not even in the software itself. As a new user, you need good support from the software. Not all of us can pick up a new drafting package and be able to use it overnight. The benefit of having a helpful expert you can turn to, whether its in person or on a forum, is invaluable. Expert help is what you are paying for when you pay the yearly subscription costs for programs like Inventor, Solidworks and Solidedge. If your income depends on making the software work, its worth paying for help. Similiarly with if you are using packages such as Turbocad or Cadian, you need good forums and telephone support to tackle the inevitable problems.