Anyone willing to share advice on how to go about a 1/2 meter heated bed?
http://blog.mechanizedmedic.org/?p=17
Easy, order one from Alirubber.
What about supporting it? And what to print on?
It would need to be attached to the under side of an aluminum plate then put a piece of glass on top to print on.
4 x 250mm silicone pads running on 110V AC off an AC SSR,
0.25mm thick aluminium heat spreader on top. Insulation underneath.
Alirubber pads (total 1500W or more), milled aluminum, inductive sensor.
Though an aluminum pad that size might be a tad expensive. But glass that is still thin enough to heat quickly enough might end up being too thin to stay flat.
Base support could use ACM sheet (Alpolic, Dibond, etc…). Maybe marine ply, not sure how likely to warp with temperature and humidity cycles though.
@Mark_Rehorst , I have an E3D Volcano kit on order so that should help with printing quicker… I really like your idea of printing big stuff on a sacrificial layer! I’ll have to do some homework to see how I can go about that for large prints. For normal-ish prints I think I want to go a traditional route, maybe using a 10" heater/glass until I want to print bigger.
@Thomas_Sanladerer & @Tim_Rastall , I’m going to price out some aluminum today, hopefully it’s in my budget. #fingerscrossed For the heater I am planning on using Alirubber but I haven’t decided if I will use multiple zones or a single blanket. I do have an 8 channel CLS208 heater controller but it uses TCs not thermistors. I would also have to manually set the temperature each time I printed, unless I can figure out how to send RS-232 from RAMBo.
For today, I’m going to go back to gathering hardware, building the frame and maybe crap out some new bracket designs.
The lowest price I was quoted locally for 1/4" mic6 was $125… I’m going to explore some other options for the time being. 
Price goes up dramatically above about 12"x12" for aluminum…still, 24" is .6m if you can cut it down a bit. But there’s no getting around the cost rising with volume.