On Jan 31, 10:11 am, wrote:
I need to install a threshold for a 45" wide door. The current
threshold is marble that is 8" wide and 45" long. It is currently
flush with the floor and there is a small gap between the door and the
threshold. I would like to replace this threshold with one that is
raised from the floor to reduce that gap. Does anyone know where I
can buy thresholds for this project?

we don't know where in the world you are. do you have a yellow pages?
look up custom kitchen countertop fabricators.