This is just an idea I was toying with a long time ago but for some reason I've been pondering it again. I started a project a long time ago that use tonal patterns for various inflections.
For example nouns having a pattern of 135 would be nominative and 531 accusative while the dative may be 411, and the locative 252, etc.
Verbs could have their own patterns to indicate tense and aspect, maybe a 135 to indicate the present continuous for example, while 13 might be past continuous, and 35 for the future.
I should also add that I'm also trying to work in a few other functions like aspiration, palatization, voicing. I just haven't gotten around to assigning them functions yet.