3- and 5-way dividers for 4x6 photo / craft keepers (such as Michael’s #10468242 or the “IRIS Extra Large 4" x 6" Photo and Embellishment Craft Keeper” on Amazon).
I use these for organizing electronic bits, but please be aware that neither the storage tote nor most 3D-printed plastics are static dissipative. No problems here but YMMV. The dividers reach all the way up to the lid, so items won't shift between compartments (very small items, like beads or coins, WILL shift around, so you'll want to group these in small containers or Zip-Loc bags).
Use draft print settings. Nothing to gain at higher resolution but wasted time.
If you’re wondering about the strange wavy shape on the 3-way divider’s walls, it’s because the lid and bottom of these photo keepers aren’t perfectly flat (they dimple inward slightly) and had to be accommodated. And that extra half-circle on the 5-way divider is so a stack of Adafruit Circuit Playground boards can go in there and you can still fish them out.