For streamer box I used cutoff of chery with at least 30 mm thickness. For dry flies box - each half about 15 mm.
Acrylic 1/8" from Amazon. Same for small magnets.
White insert from Internet search - Richard Wheatley insert. Barrel hinges from Rockler - 8.9 mm diameter.
Usual cutting instruction. I use 1/4" bit for everything, only holes for magnet - 1/8". Half-inch bit for removing most of the material inside of the boxes.
Enjoy.
Ed.