Having used Dremel and Rotary Tools for over 70 years I've managed to collect a huge number of tool bits and mandrels. Keeping them in order and being able to easily find what you want always seems to be a challenge.
I found a neat tool bit storage box on eBay made one at a time be a retired person. Check it out. Go to eBay.com.
Search for:
Dremel®/Rotary Tools ■ Storage Case for Tool Bits ■ Holds 100 mandrel/shank bits
Good Luck