Shoe Monkstrap Half Brogue

I build this 3D Model to see how much time I would need and what difficulties might occur.
I tried to match the reference from https://www.undandy.com/us/shoe-types/shoes/48-monkstraps-half-brogue-chocolate to a high degree with a cleaner appearance.
This model had to match special requirements for a browser-3d viewer called "Unlimited 3D platform". Therefore an easy change of colours and materials in the 3d viewer was a necessity.