re: Compatible Woods in Small Boxes

The wood looks great.

I would make a floating bottom with probably a 1/16 deeper dado.

With the width at 5 3/4 I don’t think there would be much expansion especially for a box that is going inside a house.

I could not find the granadillo expansion rate but here is a good link to calculate expansion: it has maple and ash expension rate.

http://www.popularwoodworking.com/tricks/how-to-calculate-wood-shrinkage-and-expansion

given the dimension and some of the ash and maple expansion coefficient, it will not be a great movement .