I have a worn out tray; it is completely unusable now so i tried to open the back side to figure out its design.
I'm amazed that the pdms is not a perfect rectangle; it has extrusions designed to sit well with the screw threads and the black gasket. I'm pretty sure the manufacturer of the tray has a negative mold for the PDMS. And unlike the old tray, they didn't seem to apply a wacker primer on the glass slide, the pdms can be detached from the glass easily without leaving any marks. Thus making the glass slide reusable. The new tray's glass slide is also smaller than that of the old tray.
Im thinking of making a negative mold of the PDMS, but i am yet to figure out HOW. I just have an idea of having a negative mold where the base inside the mold is the glass slide, then pour the pdms on it. When done, attach it to the tray; seal the corners of the pdms to the tray with a small amount of pdms or soft UV curable doming resin.
@OwenSmithyman , is there a way we can get a CAD of the negative mold, too? My wishful thinking.