This is a N Scale ladder that you can cut to length or print more of and glue together if needed that can be attached to a building, tank or other structure.
It resembles what you would find permanently attached to a structure.
You can also print a safety cage that can be added to the ladder or print more than one if you want a safety cage over a longer length of the ladder.
Another option lets you print a platform that goes on the top of the ladder where someone would exit the ladder and walk out on top of the structure.
Above is the finished ladder on a tank that you can also print out in any height you want.
More about the item here ...
http://1fatgmc.com/RailRoad/3D-Printer/page-15.html
And the files to print it here...
https://www.thingiverse.com/Sumner/designs
Sumner
http://purplesagetradingpost.com/sumner/sumnerindex.html
https://www.thingiverse.com/Sumner/designs