These headlamp adjusters are for the BMW E39 series (5-series from 1996 onwards). The originals are made of some material that gets super brittle with age, and pretty much self destruct. Thus making the headlamps aim far too low, and wobble when driving over the slightest dump.
BMWs own solution is to supply new lamps as complete units, price probably approaching $1000.
To fix, you need to take the headlamp units apart, which is actually quite easy. There are various instructions on the net, The two manual adjusters simply fully unscrew to release. The third adjuster, connected to a motor, is released by turning the exposed 5mm plastic nut 90 degrees (not all variants have this feature). One word of warning: Do not touch the reflectors, they are very easily destroyed by attempts of cleaning.
You need one of each of these per side. They will work for the early halogen units, but may need modification for "angel eyes", and I have no idea about Xenon. Note also that the shape is different from the originals. I believe these may be slightly better - the originals were limited by what you could do with casting.
These should print fine standing up. The diameter and shape of the top ball is quite critical to get a suitably tight fit. Use a healthy shell thickness (> 1 mm) and good infill, for strength.
For additional strength you can print them laying down, but then some support is needed.
ABS is probably a good choice for material. PLA may degrade over time, and be a bit too brittle. PETG may also work.