I was on a commercial siding project that had randomly sized and coloured panels and needed a reliable way to make detailed notes and measurements in all weather conditions. So, I salvaged a piece of metal stud, drilled two holes through the top, bolted on some Tyvek sheets and voila, a nearly indestructible note pad.
**dang photos are upside down - adjust your screens or head accordingly **
On the back side, the edges are folded into handles/pen receptacles but on one side, the lower part of the pen is exposed for easy retrieval and the cap is secured so it stays put while you use the pen and then just slide it up and snap it back into place after use.
there is also a rare earth magnet to secure the flipped pages.
Tyvek, for those that don't know, is a synthetic house wrap made of polyethylene fibres and is ideal for this application. its tear resistant, doesn't break down when exposed to moisture and pencil and pens transfer well to its surface without smudging. To make the holes for the bolts, I simply burned through the entire stack of sheets with a soldering iron.
I also made a smaller note pad that I clipped to my toolbelt:
Just a piece of flashing, two 1" binder clips to hold the Tyvek and a caribiner to clip onto my belt.