I initially used the material pretty much every printer comes with. Borosilcate, 1/8" thick. It's flat, cheap, and pretty simple to mount with clips.

For the average user, it's perfectly fine once set up. For what I am trying to do, it is a terrible curse.

My intent is to be able to print, edge to edge along the entire surface. Glass is notoriously bad at transferring heat, so if your heater is not able to distribute heat evenly, don't count on the glass being the same temperature in any of the 4 corners. This leads to warping, and air prints in the corners of your job.

Glass also takes forever to heat up.

I then started to use the MK3 build platform, it is 3mm thick aluminum with heater circuit built into it. Perfect! It can accept either 12V or 24V and comes with mounting holes. Pretty much a direct replacement for my printers.

I have no complaints thus far with the MK3 heatbed. In fact, I run a 24v 350 watt power supply to this bed (on the 12V) circuit and it gets up to 125C in less then 3 minutes. Pretty sweet. The build surface REMAINS FLAT WHEN HOT. That is the key point.

Here is the problem though. I use auto bed level exclusively on my machines. I print 24 hours a day. And my auto bed level does save quite a bit of time. The only problem is that my z offset doesnt remain constant, it changes whenever it decides. So this causes my extruder nozzle to dig 3mm into the bed and when it goes to wipe the bugger off after a purge, you guessed it, creates a nice deep scar in the aluminum (I use swiss AVN nozzles and I believe those are nickel nozzles). The aluminum gets scratched up, and looks terrible.

A lot of my prints require that the bottom surface of the print remain flat and glossy, this is best accomplished with a glass surface.

Now I know you will say "just put kapton tape on your aluminum, durr!". If I do that, and my nozzle decides to dig, it will destroy the kapton tape and that is a process in itself to re-tape my bed.

I am looking for a bed with all the thermal properties of aluminum and the hardness of glass (so it doesnt get chewed up incase my printer decides to become possessed).

I was thinking of putting the glass on top of the aluminum, I can already see the problems with bed temperature. The thermistor will register the aluminum temp moreso then the glass temp and who knows what temp the corners of the glass will be if the aluminum and glass are not in direct contact everywhere.

This is my dilemma, I just want a suitable platform! Either that, or figure out a way to keep my machine from changing the z offset every other print.

/rant