This would not be a good material for the purpose you need. The solution for you and by far the least expensive would be to make sure your measurements are correct and go to a local glass shop and have them to cut the shelves for you.
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Medium density fiberboard handy panels are perfect for small projects and repair work.
2 x 4 price at home depot. They are easy to transport lightweight and priced right everything you need to get a job done quickly.
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American Gypsum Drywall Panel Common 1 4 In X 4 Ft X 8 Ft Actual
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