I have a https://www.modulargrid.net/e/dnipro-modular-dot-black-panel which is a really simple Euclidean trigger sequencer with CV control. Its nice to use for incidental percussion that flutters around the main percussion and with the CV you can make it change over time.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.