I really enjoy doing puzzles, especially Sudoku. I keep some by my bedside and do a few before I go to sleep. There's something about managing to solve a problem which I find very relaxing and it helps me nod off. I also keep some by my armchair, maybe slightly harder ones, to entertain myself in a quiet moment.
However, in January I realised that I had spent over £8 on puzzle books and I wondered if I could cut this down a bit. I also realised that I was throwing out a lot of paper which is printed on one side only (junk mail, stuff I need to print for Sunday use etc.) and I decided to solve two problems at once. I went on line and found various Sudoku sites and settled eventually with 1sudoku and I'm now able to print six sudoku to an A4 piece of paper. I print a selection every week, fold them and pack them into an Amazon packaging sleeve. I can pop a pen into the sleeve and it's even more convenient than having a book - I even use the sleeve as a hard surface for writing!
Printer ink is probably the most expensive fluid to come into this house but even taking that into account this is great - and although the paper still has to go to recycling eventually, it has been very well used before it goes.