I bought something like this a while back but didn't really understand what was going on yet and when I saw how it was wired, I'm having second thoughts.
Here’s mine I built for my dads car. I bought most of the stuff from amazon. I added way more relays than I needed just incase of add on’s later or so a relay failure wouldn’t be an issue.
This is where I am now, though I do like having the option of having a box to cover things like the amazon and jeep parts. Where do you plan on installing this, it's huge! :)