I little while back I was inspired by Maria Thomas' repurposing of a canister that they now use as a home for their Micron® pens. To store my pens properly in a horizontal position, I put them in a box I have to rummage through. Not fun, and certainly not very handy. What ended up happening was, I had them laying horizontally all over my desk, and once in a while they ended up back in the box. After seeing the canister idea, I was on the hunt in my own house to find something I could repurpose. No such luck.
Not long after, I was in Staples and found this square pencil holder that had sections. Laying it on its side (with some kneaded eraser dots to hold it steady on my desk), I can put all the .01 pens in one compartment, all "the others" in another compartment, and a pile of tiles now has a home in the lower compartment! I don't see this contraption online at Staples, so you might have to actually visit the store to see if they have them. I believe they also had a black version.
Now my desk is still not clutter-free by any means, but now my pens are not part of that clutter, happy in their new little home and standing ready at a moment's notice. Because one never knows when a Zentangle moment may present itself!