Did you spill my pint? OI! Come 'ere!
Possible stair prototype
Maybe I will do stairs with shelves below. That blocks the tiles beneath the stairway and if it goes terribly wrong then there is no one to be blamed “but my shelves” (bad Sean Connery pun here)
Plastic strips and rods will make this very easy to put together. Getting the plumb 90 degree angles is the trick and I suggest getting a mini mitre box to accomplish this.
I have one and it’s been very useful.
https://www.micromark.com/Extra-Long-Micro-Miter-Box