The Staedtler Triplus Fineliner Pen Sets come with a nice cardboard insert to hold the pens in place. Our son has Ikea’s Micke desk which has a whiteboard back. Staedtler’s Triplus set insert is held in place on the whiteboard by two magnets.
It’s a great way of storing the Staedtler Triplus pens: they don’t take away desk space but are easily accessible and have a fixed place they can always be put back to.