Assembly was relatively easy, but be very careful- the very first screw we put in, slipped ever so slightly and a large chunk of the box broke right off, luckily it’s on the inside so you can’t see it. What I love about this box relative to some of the others are the open slats. Our cats do NOT like being trapped in their litter box smell  will tell us by peeing on…anything else. This helps aerate while still keeping things hidden. Great size, fits our large litter-box well, though we may size down so we can fit the litter genie in the enclosure as well. The only negative is I wish ANY box allowed for a left-side entry. I suppose if you wanted to chance it  drill your own holes you could do it yourself, but given the fragility noted above, we’re making it work.