We are able to secure mines ans stabilize there walls using wooden boards. So the are falling after a defined time.
I suggest using stone / stone pillars for stabilizing the walls of digged tunnels that don't fall or after 100 or more years. This way we an build catacombs, dungeons and secret tunnels.
storage (barrels wardrobes and other containers)
dungeons for RP
The models could be one block wide (2m x 2m) to create
small tunnels (1 block wide)
cross ways (1 block wide)
big tunnels (2 blocks wide)
big cross ways or rooms (4 blocks 2 x 2)
This only one block used four times turned 90° and build of a quarter of the upscaled smaller block
The top of the blocks could be one of the highlighted versions in this picture:
for the cross vault of tunnels or rooms like
I think that new graphics are not necessairy, existing graphics could be used. Example für tunnels with a lantern für illumination:
What do you think about?
This is a separated suggestion of an article I wrote earlier: You can find it and the answer why its not solved here:
Castle on top a hill