Hi! these were custom made by the glass enclosure installer but you can find some ready made at places such as Wayfair.com

Hi! they are attached with shelf brackets. These are standard glass shelf brackets provided by the glass fabricator. Thanks

Call a glass shop in your area and they should be able to give you pricing for shelves. The clips are sold by CR Laurence, you can look at their web site for details. CRL only sells to the trade but you can get them from the glass shop.