Is there anyone konws how to create a customer designed door or windows?   It seems that only doors and windows can be placed inside the wall, but not the fernitures or the other models.   I need to create a special glass wall, but the extrusion cannot be a negative number in customermized wall design.   Even I open on hole on the wall using Niche function, I cannot place anythign inside the hole.  Anyone konws hwo to do this?   Thanks