For my second layer I used 2 plastic dowels to support it.
May I advise that you should also ensure it with cable ties...just a suggestion, they are pretty cheap anyways.
For the ramp I bent 2 cubes into a U.
My first tries on bending cubes didn't work well, parts of the grid always broke, but I filed them and tied tape around to it's still safe.
I did however bend some perfect cubes, no broken grids, nothing.
All you do is step in the middle with your foot, and pull up on both sides with your hands. Easy - most of the time.
Anyways I cable - tied the two cubes together and put carpet on top.
There are many other ideas out there for ramps too, I got my inspiration from the picture gallery.
One picture I will not forget is the ramp someone made with little dollar store storage boxes, cuting the ends and cable tying them together. This is the address of a picture like what I mean:
https://www.guineapigcages.com/photos/showphoto.php/photo/8351
And this is MY cage, it is supported by plastic dowels obvisousily, and as you can see , my ramp is covered with carpet. Works great!