[Shannonmcn]

If the cat lands on the lid (assuming you make the same kind of lid Erin's Animals does) there is no weight actually on any of the glass on the bottom or sides. All that weight is transferred on to the metal bars the lid sits on and from there into the wooden end panels. The only weight supported by any of the glass is the weight on the bottom of the cage from what you have in it (substrate, wheels etc) and ideally you have as much direct support under that bottom panel as possible so it doesn't bend.