The QUBZI Edit / Everyday Objects
A notebook and a favorite pen make a small kit. The case is the part your hand finds first in a bag and the part you see first on a desk, which is reason enough to choose one for its surface. Below are twelve, grouped by what catches the eye: patterned cloth, long narrow sleeves with a small detail at the front, then folded, zipped and rolled shapes. The photographs show color, pattern and outline. A listed size can describe the outside of a case while leaving interior length and slot width unstated, so check those against the pen you have in mind.
Patterned cloth and a little picture
Three cloth cases, each with its own temperament.
Indigo patchwork, with small pale motifs
Patchwork squares of indigo-dyed vintage cloth and wild cotton run from deep navy to washed blue on the Indigo Patchwork Cotton Pen Case, carrying small pale cloud motifs. A full-length zip finishes it with a polished gold-tone ring pull. Against a cream or natural-canvas notebook the blues deepen; a navy cover would let them merge.

Navy dots, with small characters among them
Dots in teal, mint, orange, pink, purple and tan scatter across the matte navy ground of the Navy Polka Dot Fabric Pen Case, a two-panel case with a spine hinge; small illustrated bears and other characters nest among them. The listing mentions a teddy-bear-shaped gold-tone zip pull, the sort of thing you notice on the fourth look rather than the first. Set it beside a plain black notebook and the dots read as confetti.

Gingham with an illustrated panel
Red and beige gingham gives the Handmade Gingham Cotton Pen Pouch a storybook tone. A pink illustrated panel sits on the front, framed by a dark green pinked border, and the zipper tape is a clean mint against the check. It is a boxier shape than the sleeves that follow, and it looks at home beside a kraft-brown notebook.

For a notebook and pouch to go with the kit, see a bird journal and a green dove pouch for short notes.
Long sleeves and small front details
Narrow cases keep almost all their character on the front, where you see it as the case comes out of a bag.
A painted mouth on olive leather
The Hand Painted Leather Single Pen Case Olive borrows military aviation nose art: a shark's open mouth with white and maroon teeth, painted across the flap of a pebbled olive case with a semi-matte finish. Cream saddle stitching edges it, and the flap tucks under a leather keeper loop. The painted mouth gives the olive flap a wry focal point, and the cream stitching keeps its edge neat. A rust-red notebook would echo the maroon teeth without crowding the painted mouth.

Caramel on a long cord
Warm caramel calfskin stacks in bands of slightly different diameters to form the Caramel Leather Neck Hanging Fountain Pen Case, a cylinder with a cap that slides down over the tube and a thin flat strap in the same color. Look for the edges: they are painted a glossy reddish terracotta. Against a slate notebook the caramel warms up; against tan it would settle in.

Cat ears and a bright panel
Cat-ear corners and a soft matte surface make the Leather Pen Case with Crocodile Leather Inlay the playful one. A turquoise rectangular panel sits above a dark green animal-shaped inset, and cream saddle stitching outlines the lot. The colors are already busy, so give it a soft grey notebook and let the turquoise and green do the talking.

A flower for a fastener
Dark cowhide and sheepskin, near black, with light tan stitching around the perimeter: the Genuine Leather Pen Sleeve with Flower Button is the quietest of the group, closed by a strap that wraps over the opening to a flower-shaped metal button. A faint line of embossed cursive marks one side; the sleeve is 6.7 inches long. Beside a black notebook it nearly disappears, leaving the button to catch the eye.

Green leather, two greens of it
The photo of the Genuine Leather Pen Case for Three Pens shows two olive rectangular sleeves with contrasting teal edge stitching; one holds three pale pens at its open end. The listing describes avocado-green cowhide, teal whipstitch seams and a fold-over flap with a small punched hole near the tip. Beside a pale blue notebook, the teal stitches would come forward while the avocado leather held its own.

Folded, zipped and rolled shapes
Here the interest moves to closures — what you notice when the case is shut on a shelf.
Three stitch lines, four channels
Three long vertical stitch lines divide the front of the Handmade Italian Leather Four Slot Pen Case, a deep brown roll-style case in pebbled, matte vegetable-tanned leather, with two darker straps closing on copper-toned snaps. Tan thread traces the perimeter and every divider. A sand-colored notebook would warm the tan thread and copper snaps without competing with the deep brown leather. In the clip below the case is closed, opened with dark pen-shaped contents visible, then closed again.

Black with a red edge
Red stitching traces the lower edge of the Handcrafted Cowhide Leather Pen Case, a black cowhide case with a soft sheen and a gold-tone zip. At about 5.5 by 2.5 inches it is a compact rectangle. The indigo patchwork case and this one are both zip cases, but they lead with different things: pattern on one, a single line of red on the other. Where the indigo wants a cream notebook under it, the black one looks best with a charcoal cover and nothing else competing.

Pebbled taupe with a wrap strap
A horizontal strap wraps around the pebbled taupe goatskin of the Handmade Goatskin Leather Pen Case for Four Pens, fastening to a stitched front flap, with pale edge stitching. The listing gives a maximum pen diameter of 14 mm, so it is worth measuring your fattest fountain pen before you decide. A soft blue-grey notebook would make the taupe look cooler, with the pale stitching easier to notice.

Rolled, corded, with a tassel
Charcoal cowhide under an embossed scroll pattern in silvery grey makes the Handcrafted Leather Roll Pen Case with Embossed Pattern the most ornamental of the twelve; white contrast stitching edges it, with wrapped cords, a pale flower and a green tassel. Unrolled it measures 10.4 by 8.1 inches, with a panel of vertical slots for pens, brushes or tools. A deep plum notebook would echo the green tassel and leave the scroll pattern to carry the surface. If drawing is part of your kit, two little sketchbooks and ten quiet minutes puts a small book to the same purpose.

Start with the surface you would like to see on the desk, then check the case's interior length and slot width against the pen you keep inside.