I only needed to wait maybe four hours before I could deflate the balloons in each sphere. I then reinforced the interior of each very thin shell with water putty sausages as longitudinal ribs. Finally, I poured a very very generous amount of wood glue into each sphere and let it cure overnight. The reinforcing worked well: I actually dropped the moon from a height of about two feet and it didn't even chip.
I am amazed at how much time and effort it takes to do good Game Master prep (or maybe I over-prep). And I lament all the other hobby time lost to the RPG prep, especially when it never gets used.
I posted at the beginning of 2021 some rules I tried to self-enforce, to keep my gaming sustainable and focused. One rule was: if it's an active project, it has to fit on the drafting table. Well, we see the unintended consequences of slavishly following rules don't we. As the picture to the right shows, I've continued to cram new project after new project onto the the table until the surface became unusable as a workspace. I still like the general rule but I'm modifying to say: "if it's an active project, it has to fit on the drafting table and still leave enough room to work."