On the old board I made I used a pocketknife to individually shape the indentations but I´m lazy by nature and came up with this to get better results in far less time
I started work on a 2nd layer which can be placed on top of the dungeon tiles to expand the dungeon even further.
I didn´t want them to be as thick as the dungeon tiles because that would make moving the players very difficult.
I came up with:
cutting out the shape of the 2nd level tiles, cut the 20mm styrene in 2 halves, 10mm thick each.
Glue the tiles to 2mm thick cardboard for increased rigidity.
The next step is to glue wooden end pieces on to these tiles to raise them a little further and add weight which prevents the tiles from accidentally moving.
Here´s the first 2 of total 4 2nd level tiles I intend to make
The smaller tile fits into the bigger one for easy storage.
The next 2 tiles will be longer, like bridges, and will take up the same amount of space as one regular dungeon tile when placed next to each other. They will also have irregular shapes to create this dungeony feel.