I am cuurently working on a project designing a telescopic stretcher for medical purposes. My product must hold 170kg, extract to 1.99m in length be light and contract small enough to be carried on a persons back. I need some assistance in the diameter of section tube I would require, I have not managed to get my drawings past the initial design stage but hopefully will have used these to convert to autocad shortly. trying to get information from anywhere is like trying to find rocking horse manure!!!