I designed a few spiral vases because I wanted something to throw my small bits of desk trash into. If you want to use it for pens you'll likely want to reduce the height 20-30%. You could also scale it up. I did that and it worked nice.
The rigid version has ribs that help it hold it's shape better, but also make it more breakable when being squeezed.
The author marked this model as their own original creation.