Cut the pieces out of the 1/4" poplar using a laser cutter. You may need to experiment to get a good cut without too much burning. I recommend doing multiple passes (took my 45W laser 6 passes) with a 0.05" Z-offset on each pass. If doing it without a laser you can use a table saw jig to cut the fingers with a few tweaks. The rest of the shapes can be cut with a bandsaw or tablesaw, and a scroll saw for the intricate parts. Replace the hexagonal hole for the 1/4-20 tripod nut with a simple round hole and just fill with epoxy.
Something I should have done before doing all the gluing is drill a 2mm deep pocket for the retaining rings to sit in. Use a 1/2" forstner drill bit. See Picture 5.
The finger joints fit together really easy so all the joints can be glued and clamped easily. Cut three 2.56" long pieces of 3/8" dowel and sand down 1/4" of the end of the pieces so they fit in the spool holder with the flat-sided holes. See Picture 4.
Glue the spool holder with the round holes goes on the bottom side of the box lid, then glue the dowels into the holes and glue the other spool holder on top.