This one is kinda simple and uses just 2 different nail polishes and some striping tape.
I firstly painted all nails in 2 coats of a black nail varnish.
Then using striping tape, I taped off a triangle shape. Although it is a lot more fiddly to use tape, you get a much better, neater and cleaner result than if you were to draw the triangles freehand.
Then I used a Barry M nail paint called Denim. One finger at a time I painted inside the striping tape and then once done I removed the tape straight away to leave straight crisp lines.
Once I had finished I realised that the darkness of the colours are too close together, meaning that the design is not as noticeable from a distance. If I were to do this design again, I think I would replace the black with a nude shade.