Can I increase the size of a number of borders without altering the cell size?

[matelot2]

Hi,
I am using EXCEL to map out a set of buildings.
I have attached part of the file.
At present each cell equates to 1 foot of space.
I would now like to enlarge and split each part of the plan so that each cell equates to 3 inches of space to add more detail to each part of the plan.
Is this possible without starting again and if so how can I do it?
Thanks,
Bob.