Here the inside of my travel writing kit. I use it in my last travel to Southeast Asia.
Left: Wooden box with current writing tools. Rulers, glue, Pilot G-3, hard pencil, Pilot G-2, Pigma Micron, Zebra brush, Stabilo orange and turquoise, mechanical pencil, Lamy fountain pen, TWSBI fountain pen, Platinum Carbon fountain pen, fine brush, scissors, sharpener, sepia pencil and eraser.
Right: Case for spare tools plus tiny watercolor box, inks and tape. Still things to optimize, for example swapping the wooden box for a fabric case could save weight and volume but for me this box means a kind of ritual writing.
It's not too heavy and contains all I need. It could be optimized a lot and I'm thinking about it these days.
Some additional notes:
Wooden box is a kind of writing ritual for me. It's always in my field of vision and is part of the notebookmaking atmosphere. Too heavy and big for an optimized backpack.
Scissors are (sometimes) prohibited on flights . They are cheap and easy to find so it's worth to use them and buy new ones after flying. Otherwise paying for extra luggage only for this reason has no sense.
I'd include a waterproof bag for the notebook. Raining and humidity in the backpack could damage the paper so easily.
I've discovered a new world of watercolor colors. That makes difficult to keep this tiny box only, but this is another story.
The main idea behind this is to appreciate the power of a portable studio. Everyday a new scenario. That provides a great level of flexibility and freedom.
And again, you don't need complex tools in order to create magic. Keep near to the basic and easy to replace items.