The case that came with my Dremel was a bit small for the extra accessories I had purchased over time. I found an inexpensive 13" Project Source toolbox at Lowes that could hold all my Dremel stuff plus more.

The designs organize my bits and other accessories in the top tray. While not needed, I used double sided tape to hold them in place.

The link to the toolbox is below. I believe this is a Lowes house brand, so it's probably only available there.

https://www.lowes.com/pd/Project-Source-13-in-Black-Plastic-Tool-Box/50175969

Updates: 1/3/2021
My local Lowes no longer has this in the store but it is still available online and may be available in some locations

I added the SolidWorks and Steps files so other can remix