I guess i'm no carpenter

Don't be so down.

From this post, I think you were using cordless power tools. For which cutting long even mitres can be very hard without a jig. Yes, that is the difference between the complexity of a reflex and of a horn, the mitre cuts.

Do you live near a school?
If you do, have a chat with them and see whether you can borrow their DT facilities when they're not using them. This will give you access to a table saw, which makes things much easier (even easier with a cutlist)...and maybe even a cnc if you're lucky.

If you are building 8, I would actually recommend 1850 horns which are optimised for larger stacks (anything bigger than or equal to 4), but that's another point.

Where do you get your wood from? A lot of people on here get it cut complementarily or for a small fee at the shop.

I've built some fairly complex cabs with just a handheld circular saw.  If you're not already doing it, when doing cuts which need to be accurate, clamp a guide onto the wood to keep the saw going straight.

Mitre angles depends on how good the markings on your circular saw are. Failing that, use some kind of angle measurer to set the mitre angle.

The 186's aren't too bad to build, at least you only have things sloping in one direction!  Try doing the same thing with a trapezoid cab!

yer just stick with it and think logically, and dnt rush it, it took ages for me to build my first 2 186's. and i did it with less stuff than you, just make sure you double check all the mitres.

I built my first speakers using a hand saw, circular saw, coping saw, drill and file. They weren't too pretty but I made sure everything was airtight so once put together they actually sounded good.

The jig shown 2 posts above is something I'm using on my current build and has made my cuts much much better and they seem to be coming on ok.

The jig I use is a flat edge from a brand new sheet of 12mm glued and screwed to another piece of 12mm. You run the inside edge of the circular saw down the flat piece on top and it leaves a perfectly flat edge that you just put right on the cut line you want to make.

If you want loadsa good building tips then I'd say read Rog's guide and buy a Bill Fitz plan. Plenty of good advice from those 2 guys.

yeah first build is challenging alright. i read a lot on here before trying it. great tips in Rog's guide, and loads here in the forum. can't imagine doing it without a saw-board as described above. it was Dom's posts on these got me to make one up.

gettting mitres to turn out right, is a matter of a bit of practise, and getting to know your tools.

take your time with everything and don't be discouraged. even if you have to buy an extra sheet of wood to re cut something you got wrong, you'll still find use for the other bits, so they won't actually be wasted.

i've had loads of really frustrating moments, but it's really worth it for the first time you actually get them out somewhere and make some noise and watch people having a dance! stick with it... 8 186s is a big first project though.