Hi Guys

I have to model an object that has certain lengths.

How do I make it such that if change the lengths, the 'whole thing' gets bigger or smaller depending on the change of length(s).

I cannot do this, how do I combine the parts such that when I change the length, the whole thing is affected by it. I am really frustrated as I have been trying to figure this out since last week

Any help would be much appreciated !

Thanks