I'm sure this has been covered and I'm sure once you have seen one, seen them all, especially with kits. I could have built the cabinets from scratch, but these days, sometimes just knowing you can is enough and it's not so bad to pay someone else to do it. Plus, nobody really cares. Then there's always the leftovers that you end up hoarding like luggage. After a boat building endeavor, an industrial scale welding op, and my countless other hobbies, I try not to accumulate more than what I already have. I am not fond of MDF, or any particle boards, so the less of it, the better.
Glued the cabinets up. In my experience, with wood glue, as long as there is consistent squeeze out, it's enough.
Installed the crossovers, recommended foam, and tacked the fronts on to see what they sound like before deciding on a finish for them. They sound pretty awesome. So much so, that I procrastinated moving on with the rest of the project, Frankenclamps and all.
I made the holes for the binding posts with a homemade circle jig. Hole saws and MDF don't agree with me. Plus I have a router. Always looking for a reason to use that anyway. Plus a little roundover treatment to tidy them up.
Backers in, post holes drilled.