Ironic that I saw this topic come along as I have been searching for a good model that would work for my needs and just couldn't find such. So I designed my own.
Pretty much just a sliding post design that lets you get really dense storage in a small space. I tried multiple commercial units, but the base height was always too tall and deep sockets would not fit in the drawer. My design has a very shallow base but is quite sturdy with sliding pegs.
Right now it's just 3/8", but I'm tinkering with some replacement pegs for 1/4" and 1/2". Each peg has to be slightly smaller than the size needed, but not too small or the sockets wobble or could come loose easily.
Each rail is about 7" long, which was a comfortable size for my printer. To combine them, I just flipped them upside down and used gaffer/rigger tape to connect them how I wanted. When they are flipped back up, the sides are flush and it looks like a solid one piece design. Should be able to combine then side by side the same way if you want.
I did my test pieces in red and blue to make sorting standard and metric easier. Now I'm fighting a failing printer extruder before I can print up more. Clearly I need a bunch more as you can see.
Search Thingiverse for 2777681
https://www.thingiverse.com/thing:2777681