Essential Equipment
Even with all the devices and services at my disposal, I prefer to sketch ideas and keep notes using a fountain pen and 1mm graph paper.
This is a cherry wood fountain pen with an iridium nib that my wife bought me for our fifth wedding anniversary. I use black ink exclusively, and keep a couple of spare nibs in a bag alongside the ink cartridges.
The choice of paper is a mental thing. My brain associates it with engineering and precision, and it puts me in a free-thinking and highly-focused frame of mind.