I normally DBrand my devices i like being able to mix up the color scheme. I have also put a thin clear TPU case in it since I'm doing a swap plan to upgrade to the next big thing that comes out, but typically i don't like using cases at all.
So for my Fold 3 I'm actually retuning to using a skin instead of a case! (Case on Fold 3 makes it very bulky)
It's a "Carbon" skin. And for pen holder I modified a cheap universal self adhesive pen holder from Amazon (had to shorten it by cutting, folding fabric over and gluing).
Works okay. But I have to remove pen when charging wirelessly unfortunately.
I hope Fold 4 will have internal pen slot as Note series had...