So, introduction over and onto business
Radius v Diameter
If you've ever done anything in a family involving a circular object; pipes, tubular columns etc and wished you didn't have to put in Diameter/2 to drive a radius parameter, then the following video is for you
This outlines a method for creating the parametrics for a tube, using only Diameter and Thickness to drive it, taking your family from this (OOTB example):
To this:
A much neater solution