Built a DIY e-liquid calculator because every existing tool only handled the "easy" case.

Hi !
Quick backstory before launch on Aug 2nd :

I mix my own e-liquids (DIY vaping) for a few years, and whenever I wanted to do something a bit more complex, (remix a bottle I'd already made, or start from concentrations I already had on hand...), every calculator I found online only supported the "give me a recipe, get output volumes" case.
Nothing handled the reverse.

So I ended up building my own :
MixMyCloud, a solver that works both directions, plus a dedicated "remix" mode, all running client-side with no backend or signup.

Curious whether others here have run into something similar.
A niche tool that handles the textbook case fine but falls apart the moment your actual use case is slightly different.

What did you end up doing about it: built your own, hacked around the existing tool, or just gave up ?

Happy to answer anything about the build in the meantime !
Launching properly on Aug 2nd !