I use different colored pens for different projects when journaling, but hunting through a bin full of Staedtler Fineliners to find the color I need was driving me crazy.
I realised I had two different needs:
The solution: a custom lid for a 2x3 gridfinity bin that holds six pens on top with storage below.
Sounds simple enough, but after three iterations, I'm still making improvements.
Due to the size of the pens, and the shape of the lid - space is tight.
Version one had a lid which sat into the bin, but the pens moved around too much:
Version two gripped the pens better but was too thin to lift the lid off the bin easily:
Version three increased the lid thickness for better grip. It also improved the fit around the pens. It works well - pens stay put and the lid lifts easily:
The pens still rattle a little more than I'd like and, given the increased height, we could improve the fit.
In the next version, I'll increase the thickness a little more to be able to improve the fit. The pens will sit deeper into the lid, so a groove to be able to grab the pens will be needed. But, most importantly, I want to make the underside gridfinity-compatible. That way, I'll be able to take off the lid and place it on any other baseplate - which is important to be compatible with other projects I'm working on.
Three iterations later, I've once again learned that good design comes from testing real use cases, not solving problems on paper - or in CAD software.