Summary

This design is a modular wall display for enamel pins. You can freely print and assemble any number of tile to form any shape and use it to display your collection of pins.
The different types of hook make it easy to attach to any type of wall. The tiles are hexagonal with 55mm between two opposite sides. They can accommodated enamel pins of corresponding size, using a single needle.

I total you will need one "hook tile", as many "standard tiles" as you want, one "hook" and about 3 times as many "joins" as you have tiles (the exact number will depend on your shape). You will also need up to 5 "join hook tile" to assemble the hook tile.

The tiles should be printed face down. If your printing bed has a nice surface you wont need any adhesion structure, if not a raft will help you achieve a homogeneous look. The parts are deigned to be printed with 0.4 line width and you will have issues if you use bigger ones, but it doesn't contain any fine details and it will print well using 0.3 or more layer height.

For mode details of the display fabrication steps you can look on Instructable:
https://www.instructables.com/Modular-3D-Printed-Enamel-Pin-Collection-Display/
And for a graphic illustration on the tiles assembly process here is a video youyube:
https://youtu.be/RVnH4WTFr5Q

Edit: Following a suggestion in comments i added 3 types of tiles intended for big pins with multiple needles. "Tile to pierce" doesn't contain any holes, but just a flat surface you can pierce using a small drill specifically for your pin. "Tile small mesh" and "Tile big mesh" contain an array oh holes adapted for any pin, but the holes will be apparent if the pin is too small to hide it. Please give feedback and send me a picture if you use those models.

Edit #2: I've added two files: A "join slim" that is just a version on the join with larger tolerance if your printer prints bigger than it should and a "hook markless" that uses the small nails of the so called "markless" nails as shown in the images.

Edit #3: Pong (https://makerworld.com/en/@pong) designed feets for the display. If you prefer to leave it standing on a table instead of fixed to a wall, just insert those feets inside the dovetail grooves. The STL file corresponding to this model is called “Enamel Pin Feet”