Meshmixer is an interactive 3D modelling application with advanced 3D modelling features as well as various editing and analysis tools aimed primarily at professionals.
Its interface is perfectly designed to be user-friendly. In other words, you won’t need any kind of tutorial to start messing around with it and making all sorts of abominations.
MeshMixer is a good solution for realising 3D projects because it comes with smart editing tools and, most importantly, it’s free. Keep in mind that a powerful high-end computer is required because it consumes a lot of system memory.
If it detects that the model you created only has one 2D wall, this software solution will inform you that it is not suitable for printing. This tool will also determine if the basic structure of the model is messy or not properly sliceable.