BMW DIY howto: hardwiring using existing empty fuse slots (fuse tap alternative); E60, E61, E90, E91

I found and ordered the crimp connectors required for adding new fuse slots. On this and some comnemporar models that's 61138377734 "Double leaf spring contact 4,0-6,0 MM²(AG)".
Some told me to just use a fuse tap, which honestly is probably better in every way, except for that irrational part of your brain that just wants an install like this to be "clean". If you're one of those people, then this how-to is for you.
Still, this was much easier than I suspected. Those crimp connectors were €1.40 a piece from my local supplier.
You don't even need to remove the glove box as I've done here, at least on the E6x you could just pop off the inner footwell trim and slide a new connector into the back. I have it off because it makes this much more ergonomic, especially for routing the lines themselves.
Of course for a fuse tap that's even easier, as you only need to plug something into the front.
One thing not mentioned here is that if you're doing this on a model like the E6x for e.g. wiring a dashcam you need to take other precautions to ensure you don't run your battery out, as anything wired into the front fuse box (and this isn't the same on E9x and various other models) will run down the battery to 0% unless switched in some other way.
In my case I'm using this in combination with the hardwire kit for my dashcam (a VIOFO A129 Pro Duo). The camera itself has a "parking" setting with a timeout.
It can detect that the car is "parked" because the hardwire kit comes with both a live "battery" line (which I'm hardwiring here), and a "parking detection" line. The latter you wire into some line that's switched already, I spliced it into one of the power lines going to the mirror. It also has a hardware voltage cutoff setting, which I've set to the right voltage after some experimenting.