The Forcecage spell states:
A creature inside the cage can't leave it by nonmagical means.
And its box mode states:
A prison in the shape of a box can be up to 10 feet on a side, creating a solid barrier that prevents any matter from passing through it
The Wall of Force spell states:
Nothing can physically pass through the wall.
The description of Nolzur's Marvelous Pigments states:
When you complete the painting, the object or terrain feature depicted becomes a real, nonmagical object. Thus, painting a door on a wall creates an actual door that can be opened to whatever is beyond. Painting a pit on a floor creates a real pit, and its depth counts against the total area of objects you create.
Can Marvelous Pigments be used to paint a door or hole to go through a Wall of Force or a Forcecage?