I have used Alibre Design in the past and it was great. Even better for the price to get into parametric modeling and have so many functions. Cubify Design is basically the same thing with limitations. Thus far the biggest limitation is the export files (only STL) but it is still highly recommended. It does not have sheet metal and standard parts from what I can tell, such as gears but for a hobbyist it will do a great job. I also tested outputting the STL into Cura to create g-code for 3d printing and it worked fine. Once again I would recommend it.