For some Glass Cathedrals, you may want to substitute in a custom little person rather than the one in the standard box. If this is possible, it is noted in the product description. A custom figure can only be bought WITH a Glass Cathedral, they are not available to buy separately.
Typically, you will be able to specify the person's gender, age, hair style and hair and skin color. You may also request a specific activity pose, eg. someone doing yoga, but these figures are not always available or possible so please check with me first.