I’d like a literal thinking cap. A regular baseball hat, but with the look of an orange or yellow construction hard hat. It would say “Construction in Progress, Do Not Disturb” on it.
Here’s why. There is an annoying asymmetry between inside-head and outside-head thinking. A thinking cap would solve this problem.
People think they can disturb you when you just sit. They think you’re doing nothing but staring off into space.
You don’t necessarily need a pen and paper to think. You need peace and quiet and little movement. Just because you’re not moving or holding something, doesn’t mean you can be interrupted.