I created a widget for Android phones to help learn Mnemonica
I learnt the mnemonica stack a few years ago but because I don't perform regularly I'm not as fast with it as I once was.
I built a passive flashcard widget for my phone (free / open source / not on the Google Play store) that you're wlcome to use as well. Whenever you unlock your phone you get a new card<>number combo that slowly reveals after 2.5 seconds, giving you time to try and recall the pair.
Try it out here: https://github.com/p44v9n/android-mnemonica-widget/releases