How to cut/split an STL mesh into multiple parts by a plane

Say, you have a model too large for you 3D printer. One way to print it is to cut it into multiple parts, print each separately and glue them together. This tutorial shows how to cut a mesh (in STL) by a plane into parts. I&tried several programs and the easiest (even for a beginner) was NetFabb Basic (can be downloaded for free). In Blender it took me the whole evening to orient, this was straightforward. It is also possible to cut each part again and again so that we have many parts. The wholes are automatically filled. Hope it helps :)