Build a Private Shopify app

I want a private app developed for my shopify website. The private app will allow my customers to customize their yeti, and rtic tumblers. Please see the example of what I want by reviewing the following website: [login to view URL] Following Requirements: 1). I need all the functionality of the website example above, plus a tab for vector clip art. Ex: fonts, monograms, front and back, upload tool, and more. 2). Application needs to have a admin section where I can add front and back of products. (needs to be scalable so I can add more products for my engraving store... etc. Wallets, cutting boards etc. 3). Admin section needs the ability to add fonts for text and monograms. 4). Admin section needs to have the ability to download uploaded artwork. 5). When customers see the add to cart it needs to be changed based on a tag to say start customizing. I need the app to be scalable so I can add more customizable products in the future... I want the system to be very easy where I can develop a new design such as a monogram and add to design tool for customers to choose, while they see the text live on screen as they type.