How to resize a line between 2 nodes

I need to resize a design from 30cm to 100cm and maintain the boxjoints for 3mm ply
My way of doing this is to
Resize vector to 100cm
Break apart vector
use line tool draw line to 3mm length
drag to position and rotate to match angle
then drag and snap to end
delete original line
do same for other side of joint
change to edit nodes tool and drag end nodes to snap to new 3mm lines

or if they are horizontal or verticle
break apart
group all lines change the width
use distribute tool and move H together

Does anyone have an easier way of doing this whether it be in LB or other software.
I have included a number 2 as a sample of what I am resizing
number 2.lbrn2 (27.1 KB)