Paper, thread, and a little patience.
I am an enthusiastic amateur with a cupboard of fabric offcuts and a habit of drawing on the backs of envelopes. Delft suits this combination. A short walk gives me brick patterns, canal reflections, window grids, and more bicycles than I could reasonably count. I return home with one small arrangement I want to understand.
My interest in stitched graphs started while repairing a linen bag. I had marked a row of holes slightly out of line, and the repair formed an unexpected zigzag. Instead of unpicking it immediately, I drew the holes on paper and tried several routes through them. The bag was eventually repaired. The question stayed on my desk.
I keep my experiments in dated folders, although the dates are there to help me find a page rather than to prove steady progress. Some weeks contain ten versions of a single shape. Others contain one note that says the thread was too thick. Both are useful records of what actually happened.
This site is a personal workshop notebook, with all the limits that implies. A pattern may interest me because it is satisfying to stitch, even when someone else would find a more elegant solution. I try to explain the choices clearly enough that you can disagree, adapt the exercise, or make a better version on your own table.