Here's a bit more info that might give you some ideas, have a look at some youtube vids of the packages mentioned.
If you're working in 3D, you can work with solids or surfaces. Think a cricket ball vs a balloon and the difference when you cut them in half.
Autocad can do both sufficiently but is not great at either.
Rhino is a powerful 3D cad package that's about 1/10th the price, but only works with surfaces. This is both good and bad depending on usage. For example when you cut things you need to fill the holes, unlike with a solid where it's all filled all the time. There are many good free and paid plugins, like for jewellery production, boat hulls, propeller design, etc..
Most commercial fabricators who make a lot of small parts that join into assemblies use solids editing programs.
The best solid editing programs are called 'parametric' because they work with parameters that you can change at any time, and those changes will flow forward through the drawing. They also have ways to assemble various small parts into assemblies, which you can make move, so you can model a machine where gears turn, parts move, etc.This is a better system but it takes some getting used to the thinking involved.
Solidworks is the big name in this field with a price tag to match.
A cheap and reasonably powerful package is autodesk's
Fusion 360. Last I looked you could fudge a licence for about $50 a year by jumping thru some very simple hoops (tick a few boxes). Autocad's basically subsidising this package as they develop it to try to use their squillions of dollars buy into another market.
I made some very impressive shiny lamp renders doing the tutorial. The materials handling is great.

But then I found it lacked very grunty tools to do stuff I could do in Rhino easily, like sweeping a loft along 2 rails.
The package that I'm most excited about currently is
Onshape. It works fully in your browser and is totally free till you try to mate 50 parts into an assembly or something along those lines. No saving as it's browser based. Runs on anything, tablet, phone, etc. Share drawings
PS if you want a simple package with amazing library of stuff you can drop into your drawings then to for
Sketchup. Knowing CAD I find it a bit clunky to use but often I'll export models from their warehouse and drop them into other packages. And if I knew nothing it'd be very simple & logical.