step file adjustment

[freto036]

Hey everyone,

a friend of mine printed the cases for me, however, my circuit board apparently is 3mm bigger than what the case was made for. He can't seem to only change the length of the file and while I had a quick look at it, I have absolutely 0 knowledge about changing CAD files.
I have found out that FreeCAD allows to scale single axis by whatever multiplier, but I can't seem to figure out to get measurements in order to scale with the right multiplier. Does somebody already have that file adjusted by 3mm (inside length) or can point me in the right direction as to how to solve this issue?
That would be greatly appreciated!