Glas plate holder for bed Ender 3

Edit 17.02.2019

1. I added Bed_glas02_big_hole.stl with a larger hole.
2. I added Bed_glas03_big_hole_3mm_thermal_pad_insulation.stl with a larger hole and 3mm higher under Thermal Heating Pad Insulation.
Example link:
https://www.banggood.com/2352353mm-Heated-Bed-Hotbed-Thermal-Heating-Pad-Insulation-Cotton-For-Ender-3-3D-Printer-p-1369364.html?cur_warehouse=CN

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Just 3 pieces to print.
I applied technical vaseline under the glass.
It improves the adhesion and heat transfer th