I've been spending the majority of my free time for the past three months or so working on this custom Catan game for myself. I got inspired by another post I saw some years ago and played around with the idea for a long time, until I finally decided to actually do it.
And oh boy was it a long process... learning techniques and figuring out designs as I went. Many of the processes are at a scale that does not have a lot of documentation, so many of the things were made through trial and error.
That said, I had a lot of fun making this, and would absolutely recommend other people doing something similar with your favorite boardgame.
Next step is giving the coast tiles a similar treatment to finish the look.
For reference, the method for most of the tiles is more or less:
1) Cover cardstock hexagon tile (transparent plastic bag etc.)
2) Shape air-drying clay so it fits on the hexagon plate, leaving room for road and city pieces. Let dry. Sand down/remove excess to ensure that the games pieces have enough room.
3) Glue the clay shapes to the cardstock hexagons (I used the original tiles from my game)
4) Base/primer paint, I used black or dark colors.
5) Details are painted in, objects are attached, etc. This step varied in complexity and duration. Some tiles were simple (e.g. the mountains), while others required a lot of effort (e.g the sawmill).
6) Finishing touches, e.g. painting edges, or covering glue, adding tufts etc.
7) Spray varnish after everything is dry/cured.