Rulers - or rules.

[Bod]

Wish I could find a steel ruler with mm on both sides (well all four edges if you see what I mean) and just mm, they all seem to have half mm normally for the first 100mm which just give me a headache

Look for a Moore & Wright No P421mm rule.
This has single millimeter divisions on top and bottom of the face side. Clear and easy to read.
Good luck with finding one, I've only ever seen 2, mine has been coverted many times at work, hence it is clearly engraved as mine!!

Bod

 

[Cheshirechappie]

Mitutoyo offer 6" and 12" stainless steel rules both flexible and rigid with 1mm divisions on at least one edge - http://www.mitutoyo.co.uk/small-tool-in ... ations=351

Moore and Wright also offer similar rules, with the mm only on the top edge on one side, and on the bottom edge on the other; however, they don't seem to sell directly, so a bit of googling to find a retailer would be required.

Both maker's offerings are satin-chrome finish, which (agreeing with Peter Sefton and Racers) is the best finish for steel rules - easy to read in almost all light conditions except pitch dark, without glare or awkward reflections. It does seem to be a tough and lasting finish too; I've had my 6" Rabone Chesterman 64R since 1981 and it's still in excellent condition, despite not really being pampered.

 

[Stuart]

I have a 3 foot folding rule and use it when spindle turning and rarely unfold it, if it touches the turning when I am marking out it does not fill me with dread that metal rules touching spinning wood do.
As joiner for nearly fifty years a 16 foot tape has been part of my going to work kit and clipped to my belt, same as a pencil behind my ear.
I have only ever worked off paper rods when shop fitting and the rod went with the job, first to the wood machinist, then to the joiners with the prepared timber and then onto site with the job. It was a very accurate way of working and few mistakes were made.
Joinery shop rods were drawn out on birch ply, in the case of stairs only the height was drawn out on a batten as Jacob described and set out with dividers. The newels and winders (or kites) and easing on the strings were set out full size on the ply and with dividers, trammel points and a batten, 16 foot tape and a roofing square with the veritas nuts the whole staircase could be set out and made very quickly.
So a rod for setting out is essential for me when setting out three dimensional work and a a 16 foot tape,
for toy making a Starrett combination square

 

[boggy]

A very useful rule is one with the zero in the centre and scale increasing to left and right. With one of these you can find the centre of a piece of wood instantly. Axminster sell one but unfortunately in Imperial only