I'd like to propose another simple simple simple solution, to carry your pen with your moleskine without building anything.
This solution does not require you to modify your notebook. All you need is... well... a pen.
let's get started...
Step 1: Clip that thread!
Step 3: Pull!
Step 4: Block it!
now you can carry your pen with your moleskine wherever you go. easy, isn't it?