Truth be told, using Alibre for this little pissant project was a bit of overkill, not really necessary at all. But I find using Alibre kinda fun, and if I don't use tools like that once in a while I start to forget how to use them. Where Alibre really shines is when designing something with quite a few parts that need to fit together and work together. It's good for playing "what if" because it's a parametric solid modeller. You can change a dimension in a part that's in an assembly, and everything in that assembly affected by that dimension will change in response. When you get your model to your satisfaction, it can then generate dimensioned drawings of every part and assembly. If you later change a dimension in a part, all of the drawings of that part and assemblies affected by that part will be changed accordingly. I think it can also produce output compatible with some CNC systems but I don't really know anything about that.
I once attended a free seminar hosted by the local SolidWorks dealer. I have to say that Alibre is not in the same class as SolidWorks, but SolidWorks is way beyond my play budget at several grand a seat with annual maintenance not optional -- ya gotta pay to play. Alibre does about everything I want to do, albeit not always quite as easily as SolidWorks, and its price was commeasurate with its value to me.