glass plate fixture, but tends to warp the bed!

These are replaced by:
http://www.thingiverse.com/thing:402188

I don't like the clamps which keep the plate on the heatbed in place..
The fourth one is divdided in order to fit the connection.
After printing I noticed the glass plate is smaller than I thought,
I've to lower the height 1 mm and widen the edge also another mm.
These are labelled V2, I haven't made them yet!