Halters and horse gear
A rope halter is knots and measurements, almost nothing else. Every knot sits at a point that has to be right on the horse.
Sizing
Halters are sized to the head, not to the horse's height. Nose band, throat latch and poll all have their own measurements, and a halter that is close but not correct sits crooked and rubs.
Material
Thicker rope than most paracord work. Six to eight millimetre PPM or a dedicated halter rope holds the knots without cutting into the head.
Knots
Placement matters more than the choice: the same knot in the wrong place changes the pressure points. Marking every position before tying anything is the only reliable method.
Buying
Halter rings and rope are listed here: halter rings (https://www.123paracord.co.uk/paracord-supplies-and-accessories/halter-rings/).