My take on a CNC vise Parallel storage solution. Each set of parallels sits coplanar at the top and arrays deeper into the storage container as they move away from you. They fit snugly but have drafted openings with heavy chamfers not to be annoying. As preset it's for .125" x 6" pairs of parallels.

Printing

I printed this on a Bambu X1C in Prusa Galaxy Black PLA and White (not sure which). To color change the text, see your specific slicer for instructions - most can do this quite easily (do it by Z height).

• You shouldn't need any support.
• It's printed at 0.2mm layers with lowered spacing at the top to 0.08mm to get finer details on the top.
• 8% Support Cubic infill.
• I also used All Top Surface ironing to make it more impervious to oils.
• This took 9h 12m on the X1C.

If you wanted a metric version it shouldn't be too hard to update the text and any appropriate dimension changes needed.

Adjustability

• You can change basically everything in the Fusion 360 file.
• Keep in mind it's VERY slow to adjust any features largely because of the text items.
• It's parametric in all the good ways you'd want for Gridfinity including the base grid size (GridXY). We use a 50mm grid compared to the 42mm size. I've provided both in 3MF files. 
• To adjust the model in Fusion 360 - first change the parameter for BinWide and BinDeep which will change the number of cells needed to be consumed for the container.
• If you want to change the text labels open up the Text sketch. Again very slow.

Other

• These 2x6mm magnets fit nicely. (Amazon affiliate)
• 10 pair Parallel Set