These black or gray geometric decals in the shape of a Triangle will work great - not only for your modern nursery/children's room décor, but also in any other modern space. 

Includes:
1 Pack Includes 50 1" Individual Triangles
25 Dark Gray + 25 Light Gray OR 50 Black

Materials:
High Quality, Self-Adhesive Oracal 631 Vinyl

Made in the USA

Application:
Suitable for clean, smooth, or lightly textured walls. Some surfaces may not be suitable.