The Gestetner Copier I used was a descendant of THIS. Mine was a manual copier where I had to crank each page out at a time. You had to have a good ink supply and you needed to check the pages coming out the other end for issues. No matter how neat I was, usually I'd end up with ink on my hands and elsewhere by the end of it all. Each stencil only printed one side of a sheet, and double sided pages needed a second run with the previously printed pages and the stencil for that side. There was usually anywhere between 1-5% attrition on a run before I finished.
The Cyclostyle was quite distinct from the Mimeograph (see https://en.wikipedia.org/wiki/Mimeograph). Both used stencils to print pages, but stuff from a Cyclo was almost always in one colour ink (mainly BLACK) whereas Mimeo stuff (often used by schools) was often seen printed in several colours. That must have taken a another run through the mimeo with those sides using a second stenvil and a change of ink. Mimeo produced stuff always looked blurry.
Sometimes I miss those days. The fanzines (which started out as a gamezine running postal Diplomacy) required a certain degree of preparation and thinking, but mostly it was all straight out of the head unedited stuff, types and misspellings included for free. In many ways fanzines were one my first creative pursuits.