MP mini select bed clips. These hold nice and tight with the stock aluminium bed, a .04" or 1mm thick piece of glass and the same size piece or PEI. The PEI I am using is from Gizmodorks and the glass is from a dollar tree frame 5x7. This can be done with just 4 clips but I recommend 6. Feel free to edit, share or shoot me questions.

UPDATE: After about 12 hours of printing with the bed at 60, I can safely say heat is not effecting the clips.