Spawn the Parts within the max values of the X and Z axes (assuming this area is aligned with the X and Z axes).
So a random X value between the min and max X values and a random Z value between the min and max Z values. Let’s call the lower left corner 0,0 and the upper right 15,15.
Now do this
if X is > 5 and < 10 and Z is > 5 and < 10 then return end
spawn the Part at X,Z (since it’s not in the center area)
end