Then I made a lid. 2.25" square with small strips on two sides. I glued it to the top.
I then, LIBERALLY, squirted hot glue all over the thing. I did one side at a time, covering the edges and the corners, dripping a bit each time.
It's hollow on the inside so that it could "engulf" a mini or two if necessary.
It feels heavy and pretty solid. I think the glue really reinforced the plastic.
Here's the final result --
EDIT - By request, here are some more pictures --
|You *might* be able to tell that the open side is near Collen
|Collen being dissolved by the Gelatinous Cube