1/8 Inch Glass Clips

I needed a better way to hold my glass down and adjust for relative print bed flatness. These clips extend half a millimeter less than 1/8 inch below the top of the glass (to allow for some clamping pressure to be developed, and to mix Imperial and Metric units). I am using some 1/8 inch architectural glass cut to 8 by 8.5. As to vertical compliance, I rejected the volume-robbing strategy of using springs, but opted for 1/8 inch neoprene washers. Seems to work, but I am concerned that heat will affect either short-term or long-term elasticity of the washers, and ultimately, the hard-won level printing surface that I have created..