Fast tools make sketches faster. Slow tools change what you think about while you're working.
I keep a sketchbook, a knife, and a stack of unsorted cardboard near my desk. I could do almost everything I make at the screen instead. Figma is faster. Rhino is faster. Procreate is faster. The faster tools win every comparison except one — they let me move so quickly that I stop noticing what I'm doing.
When I cut cardboard by hand, the geometry argues with me. The angle has to be physically right or the panel won't sit flush. I can't ctrl-Z the cut. The slowness of the tool forces me to commit, and the act of committing forces me to think. By the time I've made the second cut, I usually know more about the design than the digital version could have told me in an hour.
This is not nostalgia. I use the fast tools too — most projects start in Figma or CAD and stay there until the proportions feel close. But somewhere in the middle I switch to something slow, on purpose. The slow tool catches the questions the fast tool sailed past.
The most useful thing about slow tools is that they make scale honest. On a screen, every size is the same size — the canvas zooms, the units lie. A piece of cardboard at 1:1 doesn't lie. You hold it and you know.
I'm wary of the version of design culture that frames speed as the only virtue. Speed is a feature, not a value. A fast tool can produce a hundred bad options in the time it takes a slow one to surface a single right one. Either output can be useful. Pretending the fast tool is always the right tool is how you end up with work that's correct on screen and wrong in the room.
I keep the knife on the desk for this reason. It works at one speed: mine.