Awesome! I'm jealous.
I wasn't criticizing any methods, just pointing out end grain butt joints alone (w/o rabbets or nails) are not considered nearly as strong by prof. cabinetmakers or glue companies, esp. for normal PVA glues. Half of the veneers in plywood ends are LONG grain.
Box making is a separate hobby of mine for years. If I do try box joints, I might kick myself & be in the shop for a week straight! Miters w/ Birchply would be challenging. These boxes look super - wish I were done.
Good point about making top & bottom same .25" dimensions/thickness; the added durability of .25" & convenience of same width grooves (in lids & bottoms) outweighs the weight saved by making lids 1/8" (.125").
Has anyone else discovered VIRGIL's rootbeer swingcap bottles? 3.2" width (close enough to combine w/ old Grolsch 3.05" at base), and I like them much better.