A window that is not square, a camper berth, an old curtain worth saving rather than replacing. The work that has to be measured in place, because no standard size applies to it.
Most orders resemble another order. A living room, a bedroom, a bay window: the opening is square, the dimensions are ordinary, and the craft is in doing a known thing well.
Then there is everything else. An arched opening in a house built in 1910. A boat. A bed a grandfather built by hand. A length of cloth someone carried back from a trip that now has to become something. These take longer to work out than to sew, and they are the ones I enjoy most.
They all start the same way: I have to see the thing. Not a dimension over the phone, not the nearest standard size. The measurement is taken in place, or you send me photographs and I tell you what is realistic before you get attached to an idea.
A good pair of curtains lasts decades. What fails first is almost never the face fabric: it is the lining eaten by UV, a hem that has let go, a heading tired after twenty years of opening and closing.
Replacing the lining on a panel whose face is intact is routine workroom work, and it costs a fraction of a new pair. It is also the only way to keep a fabric that is no longer made. I do length alterations after a floor change as well, and repairs on pieces bought elsewhere.
A camper has no standard window. The openings are small, often wider than they are tall, sometimes set into a curved wall, and rarely square. You work to an eighth of an inch, around cranks and obstacles, with fabrics chosen to move without wearing through.
It is the most demanding sewing I do, which is why it sits here rather than filed among ordinary services. The same precision is what a house needs when one window refuses to be normal.