Some times organization doesn't need to be fancy 3D printing. It turns out that the #00 Coin Envelope ( approximately 1 11/16" x 2 3/4" or 42mm x 70mm) is the perfect size to fit inside the Raaco Handybox inserts. Perfect for parts with lots of different values (ie resistors and capacitors) that, if kept in separate inserts, could take up whole trays themselves. 

Not everyone carries these small sized envelopes but a quick search of "#00" coin envelopes does yield a few places: staples, envelopesuperstore and suppliesshopes. Expect to pay $12 for 50. Or $22 for 250. I've only found them in white and brown but other colors could certainly contribute to additional help in organization. I did found one place selling 1 3/4" x 2 3/4" envelopes. 

And you can certainly mix and match with other inserts.