A bit of bit organization was the theme for the day.  Customized tool storage is one of my favorite personal applications for 3D printing.  The two holders on the left have narrow column spacing to maximize density and wide row spacing to facilitate finger access.  The one on the right was design specifically for the nut driver set taking into account the individual size of each bit.  I spent less than an hour designing all three of these bit holders and am sure that investment will pay dividends over a lifetime of quick access to the tools I need.  Pictured below is a CAD view from the underside.  The holders are designed to use a minimum of material and to prevent wood dust from accumulating at the bottom of each cavity.