This is pretty awesome. Although disheartening that you ended up spending much more than just buying a Yoto player or Toniebox. But I'm sure the learning and accomplishment have been worth the expense.
The tools are definitely a big expense, but are in constant use for other projects, so ammortize.
What's not factored in is the time spent working on this. I don't feel too bad about it, as working on this essentially replaced watching shows or movie at night when everyone is asleep.