Blender is very powerful.
The GUI takes some getting used to but once over that first step it is easy to use.
There are a few key features that makes it easy to go from a coarse low-poly design to a smooth high-poly design that looks great as a printed item. These are available as so called modifiers (non-destructive modification) which in essence gives a preview of the resulting model before actually applying the feature to the model itself. That means it can be modified and removed if needed.
- 'Subdivision Surface' : This is a modifier that applies something of a B-spline function to a low-poly mesh creating a smooth surface.
- 'Solidify' : This is a function that applies a thickness to a model. It works very well. Just define the minimum wall thickness to a model and apply it.
Those are just two functions but they surely make the design work a lot easier. Note that Blender is not a CAD program in its functionality. Some complain that it is hard to design an item based on exact dimensions and lacks accuracy. It is true that Blender does not have the usual functions for that kind of editing but it is certainly possible to design based on exact dimensions.
Check it out, it is free.
A good companion to Blender is DesignCAD 3D MAX. This is a low cost classic 3D CAD package for less than $100. Download and try for free.
This is a great tool to design with accuracy. It is not one of the modern parametric CAD systems but works like an old-school drafting system. It is excellent for designing the coarse low-poly design that can be exported to Blender if you like to give it a more organic and smooth touch.
It can export to dxf but I use a macro that exports to obj files that can be imported directly into Blender.
Try it for free for 30 days.