This is one of my most refined designs i use everyday. Its a bit box for ¼" bits and a standard bit extension. The design uses Magnets (As do all my box designs) You can put the 4mmx2mm magnets in each hole if you would like, it makes for a nicer case where the bits stay put, but it is a bear and takes time and patience.
Magnets needed for the lid are 8mm x 4mm (4)
For each bit hole hole and extension are 4mmx2mm (107)
If you buy these magnets in a larger pack then you can also use them on my other box design which use the same size magnets.