Cultivating angel trumpets is something for more experienced hobby gardeners. However, their propagation does not pose a great challenge, even for beginners. The cuttings method works here without any problems - even just with water.
The cuttings of the angel's trumpet also root in water
Root angel trumpet cuttings in water
The easiest way to propagate an angel's trumpet is to use the usual cuttings method. The success rate is extremely high here and is therefore preferable to seed propagation (unless you have the right to breed new varieties). Normally, a cutting that has been cut cleanly from the flowering region is allowed to grow in a pot with potting soil - this way it can connect its roots to a soil substrate straight away.
But angel's trumpet cuttings can just as easily form their own roots in a glass of water. The advantage of this variant: You no longer have to worry about the cuttings, at least as far as keeping the water moist. Instead, you just have to wait 2-3 weeks until it has first formed knobbly roots and then a tender root system from them.
However, the rooting water should be replaced from time to time. Otherwise there is a risk of rot.