These crochet horns, with four different size options as well as broken end variants, are worked in the round as a spiral.
The base is designed to be worked through the back loop only, leaving the front loop free to add accent ridges all around the outer surface of the horn afterwards, providing more depth and texture.
There are suggested beginner resources for each technique used, including for left-handed crochet! The pattern has information throughout where working left-handed can affect the result and how.

The third photo shows the four different sizes, as follows:
Bighorn (peach and green)
Approx 35cm / 14 inch strongly curved horn
Requires about 50m for the base and 30m of yarn for the ridges
Bison (purple)
Approx 20cm / 8 inch horns with a medium curve
Requires about 40m for the base and 20m of yarn for the ridges
Billy (blue)
Approx 15cm / 6 inch narrow horns with a medium curve
Requires about 20m for the base and 10m of yarn for the ridges
Bud (grey)
Approx 8cm / 3 inch tiny horns with a small curve
Requires about 10m for the base and 5m of yarn for the ridges
(For a pair of matching horns, double the amounts)
Each size of horn can be sewn in various orientations to a headband, hat, or hood to create different looks!

The pattern is 23 pages long with lots of photos showing various options and construction tips.

The horns can be made in different weights of yarn as long as you adjust your crochet hook to keep the fabric firm - thinner yarn will result in smaller horns, while anything thicker will produce larger ones. The hook size should be quite small compared to the standard used for the yarn as a dense fabric is required to hold the curled shape.

The pattern pages are photo-free and can be printed in black and white. In all my patterns I use minimal colour coding, and always include other tells (usually shapes or symbols) so that colour is not vital to the pattern, to make it colour-blind friendly and easy to follow in black and white.