I originally ordered the next to biggest size, but cancelled the order and went for the bigger one because in our house we needed to go a tier higher. This didn't alter the delivery day and I had it two days later.To adapt it for our needs I took one row from the floor width and used it as roof height, this means the kitten has access to the windowsill to watch the birds but he can't escape onto the top of the cage from the window area.I have not put the door on yet, or part of the roof, this is to introduce him to it slowly and not have him feel caged-in.For us we needed a time out area because I have an 14yr old, an 18yr old female, and an 8 month old male Maine Coon X kitten who doesn't have a lick of sense yet, and he is a mile a minute.So about the build and quality: it's functional, no jagged parts, strong enough for a cat (I wouldn't chance a dog in there) and handy to assemble and de-assemble. You get a lot of extra cable ties, which is great because I'll use it outside in summer and there are plenty left for when I have to cable tie it again.Could do better:1. The four door panels need to be double width because each panel is the same size, so if you are curvacious you are not getting through that door to clean out the cage. This would need a design fix, of course, because even if I strapped a door to a normal cage panel, with some of the handy clips and cable ties it isn't rigid.2. Having to have a frame panel underneath every single shelf panel means the floor area isn't very useable, most cat litter trays are slightly wider than the frame panel allows for, and the cat standing in the tray needs more headroom than they allow for too. So on mine, as you can see in the picture, in order to secure the highest shelf and stop it from sagging with the kitten on it, and so that we have space for the cat litter tray beneath, I had to improvise with an old extendable metal curtain rail (pulled apart). I cable tied them to the outside of the cage and underneath of the shelf panels at each junction to prevent it from sagging and to offer rigidity. This too could be covered in a slight design alteration: a couple of slim metal strips which are foldable to adapt the width (like a foldable ruler) would offer the same support as my curtain rails.3. I don't know how the lovely soft vinyl panels, the ones for the floor and shelves, will do on the flagged patio when it goes outside, a pebble or bit of garden debris underneath may puncture them when they are walked on.Honestly, for that price I wouldn't expect to have to help improve the design, but hey-ho, it has to work for what each individual needs and the two things I've mentioned here are the most likely to prove problematic.That said, I am happy enough with it, which is good, because sending it back would have been a nightmare if after assembly I found it wasn't fit for purpose, so do your measurements and prepare to improvise.