Sounds good. What material are you using to make negative mold for PDMS? Are you going to use PDMS also? I have read that to release pdms master from pdms negative mold, you will be needing a release agent before pouring pdms to it.
I also have the same question about glass slides. The size of the new tray's glass slide is different from the old one. The new tray's glass slide is 71mm X 46mm. The old one is 75 x 50mm, this was their supplier: https://www.tedpella.com/histo_html/slides-large.htm
I don't know if they have something for the new tray.
Unlike the old tray, they didn't seem to apply a wacker primer on the glass slide of the new tray, the pdms can be detached from the glass easily without leaving any marks. Thus making the glass slide reusable. Have you tried detaching the pdms from the glass slide?
I'm also curious if we can use acrylic plexiglass such as this:
You can also get this, but you have to cut the glass: