Looks really cool!
One thing I'd be tempted to do to it - when you hit your fraction "bang on" (or, at least, as close as you can given there's inevitably some which are 0.00005" "off" from the decimal conversion) - have the scale change colour. That way, when you're woodworking, you can pretend that you're being accurate
What's that they say about great minds? Anyway great or small, that's what I was thinking
I'm already at 50 on the grey-scale so rather than just dim , I'll try flashing it , if that looks pants , I can easily throw a border around it - or maybe invert ?
[edit] I was going to just use the displayed accuracy , so if display is set to 1dp it'll be +/-0.1mm etc. I'm also planning for a '@zero' output (probably logic level or O/C and relay)