1. Based on the item in the pic sent via email.
2. Use brown distressed leather.
3. The size of the Microsoft Surface Duo phone is : 14.7 cm x 9.83 cm x 1cm
The size of the pen is: 13.8 cm x 1.0 cm
4. Add a pen holder inside the case.
5.Make sure phone power button doesn't touch anything inside the leather case.
6. Add a leather loop at the back of the case to fit a 3.8cm width belt.