Is there any way I can make an artificial Dungeon?

[Astigmatisme]

I just recently found out that it's impossible to make an artificial dungeon using unnatural brick walls. I also used mods and TEdit but the results were the same. If anyone knows how to make an artificial dungeon using other means please let me know. Thanks!

 

[Dragonlord]

You might be able to use TEdit, but you need to make sure the new background walls you place down with it are not marked as player placed.

 

[Astigmatisme]

I already tried using TEdit but it's still doesn't work. I'll try to find some other technique but if anyone know a working way to make one please do tell me