I just published detailed description of how I built the Smart Mirror on Instructables: https://www.instructables.com/id/Smart-Mirror-Using-Broken-Android-Tablet/
It describes how I assembled the whole thing and touches a bit on the software side. As the tablet I reused was very old (Android v2.3) I had to develop an application to show time and weather from scratch. The source code is available at https://github.com/audrius-a/smart-mirror.git