A personal project that's been frustrating you and could be solved better in the new language/framework. This gives (a) motivation to do something in the new la

A personal project that's been frustrating you and could be solved better in the new language/framework. This gives (a) motivation to do something in the new language (b) gratification from the new language/framework's new features (c) low risk since it's not work. Almost everything I have picked up by myself over past few years has been this way. Golang (frustration with concurrency in Python), JavaScript/React/Redux (frustration with "native" GUI frameworks), Android SDK (Speed, sensors pre-html5-webview), GraphViz (frustration with "project management") etc.