For a hay rack I used a "packet pal" from home depot, in the organizational shelving section. It was about 2 dollars, and works great. Someone on this site had reccomended it, and I love it. It hangs right onto the bars, and costs way less than a typical hayrack. For the upper level I first made the upper level separate, than set it on top of the cage and attatched it with cable ties in a bunch of places. I used a grid for the floor, and put a piece of coroplast over it. I then put a piece of fleece to lay on. If you wanted to use regular bedding up there you would have to make coroplast sides as well, like on the bottom, to hold the shavings in. If this sounds like a lot of work, and you just want the upper level to be a few grids big, like 2x1, you can keep the cage one grid high, and attach the floor of the second level midway up the wall grid. So the cage is only one grid high, but the area under the "loft" or whatever is 1/2 grid high, as is the area above the "loft". I found this easier, and it took less grids to do. And I didn't need a ramp or anything, I just put a brick on the ground nearby so they could hop up easier.