Here are some of the apps I learned from Steven Anderson and which you can use to create your customizable apps. Enjoy
This is a cool web tool that enables users to easily and instantly build a rich content based app. Just paste in the URL of the website you have and then start customizing it app the way you want. You can add images, videos...etc. The free version is ad supported but there is a paid version with no ads.
This is a Google supported platform where you can get to create awesome apps using just drag and drop. It enables you to customize the look and feel of your apps, add buttons, attach objects and many more. It requires a Google account.