Using glass makes is easier to start your next print, because you can use clips to hold the glass to the heated bed. By just switching the glass plates you are ready for you next print. You can usea piece of kapton to stick a thermistor on top of the glass, for making accurate readings of the bed temperature.
This is Borosilicate glass which has little thermal expansion.
Warning: these glass plates have rough edges and are very sharp. Be careful. Also the corners and edges may have little imperfections.
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