I used a Dollar Store round cake carrier..That one my Son used the hole saw * I barely had to sand it..My one before, I burnt the edges w/ a lighter, after cutting it w/ a box cutter.
I just keep the first one, in case I need a back-up.
I also have a smaller, "one glider only" rectangle, and put it 2 floors below, that I used when Willow was being a witch about the big kitchen..Widget didn't actually eat from it alot..but I felt better knowing he had an option..They have since resolved the spatting (can't say he ever fought back).
I don't know how peeps keep up w/ the mess, without a kitchen..I would have to say, my 3 top glider necessities (aside from the obvious cage) would be: Pouch, Wheel, Kitchen.