Download it here! https://play.google.com/store/apps/details?id=giampy.simon.customcalculator&hl=en
This is the app I made in 2016. It took me months for learning how to program Android applications using the official tool Android Studio. I learned everything by myself, so I'm a self-taught person. It took my a long time to create this app despite being a "simple" calculator.
I named it like this so it can be easily found as the first result when searching for it.
The code hasn't been updated since the release on the Google Play Store. I don't have enough patience to update it. It currently supports Android API level 23 (Marshmallow, Android 6.0). But my app should work on newer versions too.
This is a calculator that allows the user to customize the interface and some buttons. There are various themes and colors combinations to chose from. This way the user experience is better and customized.
The purpose of this app is not to make money or create a unique application which is different from all the other on the market. In fact, when I created it, my final scope was to gain experience and learn how to create mobile applications, in the specific Android Applications. Then, when I thought it was ready, I published it on the Play Store, and since then it has been downloaded several hundred times, from all the countries of the word. I'm proud of it, even though the app has a few little flaws and bugs. This app meets Google's material design guidelines (I hope, lol).