If you want to make your printing platform flat enough, ideal stuff is glass sheet. Tempered Silicon glass is rated for higher temperatures than normal sheet glass making it a better material for use as a heated bed. After cracking a few sheets of normal glass from rapidly cooling or heating, tempered glass will quell your frustrations.
Size: 213mm x 200mm x 3mm
Package includes: 1 x Smart glass
Please note: The other products show in the picture are not included!Made from tempered with high transparence