As requested! The tutorial steps are under the cut.
I don’t make many tutorials so this was also an experiment in using gifs (which was not particularly successful, so sorry if they’re hard to see!).
I used a cream based makeup for this because it’s inexpensive (what you’ll find at most Halloween or party stores) and easy to blend. If you want your horns to last through a Halloween party, however, you will need some quality barrier spray. Cream makeup will not survive sweat or bobbing for apples.
1. Outline the shape you want using white eyeliner. If the outline is messy that’s ok; you can wipe away stray marks and we’re filling in the middle anyway. (Hint: To make both sides sit evenly on your face, hold a pencil/brush against your nose.)
2. Fill in your outline. If you want them bigger or smaller, now’s the time to expand the outline or use a q-tip to wipe away excess.
3. Draw a circle wrapping around the base of your horn. Use a brown that’s several shades darker than your skin so it stands out.
4. Blend it out, but not all the way. You’re spreading out the paint to create a shadow, which helps the illusion of raised/sunken skin. The circle you drew should remain darker than the skin around it. ONLY blend below the horn and slightly to the side.
5. Draw two lines under your circle, leaving space between them. This shows where the horn is “embedded” under your skin. Don’t make them higher than the base of your horn – you can see me make that mistake in the image below.
6. Mistakes are easy to fix. Wet a q-tip and erase the spot, or, as shown, dab some foundation on top of it and blend. You can also go back in with the brown and darken the shadow closest to the base of the horn, or use white to erase stray brown marks from the horn itself.
7. Add grey shadow to the base of the horn, right against the brown base, to show depth where the horns meet your skin. Add another shadow on the inside curve of your horn, depending on the shape: mine curve inward, so I painted grey on the sides closest to my nose.
8. Brighten the outer edge of your horn with more white (if needed). Outline the horns in black.
9. Clean up your edges and any mistakes with a q-tip or extra paint, then set the whole thing with powder and/or spray. Embellish as desired!
[Both horns visible in top image if you want a front view!]