I am still trying to understand the Black Art of 3D printing. One thing that I have noticed is the build cabinet temperature makes a huge difference to the flatness of a PLA print. So I have been keeping it at 28-35C and getting great results. Looking for something to make I decided to modify the rear name plate on the build platform to incorporate a digital thermometer. The unit I am using can be found on EBay for A$4-5 and is sold as a fish tank thermometer. Hope someone else finds it useful.
I found that the original design could get in the way of the gantry when you were levelling the build plate. I have reworked the whole back plate to eliminate this problem. Tilting the LCD backwards also make it easier to read.
Sorry if this has caused any problems to the people who have downloaded the first version,
Lesson learned is to make sure you throughly test before uploading things!