Buy balloons on Amazon (paid link)
Buy an air pump on Amazon (paid link)
Here you will find stand alone balloon pyramid sculptures.
Also, I use pyramid shapes as a base for making many more complicated balloon sculptures.
It's hard to mention all examples - but you got the idea :)
How to make balloon pyramid -trianular base
Balloon pyramid - square base perfect for heads of animals
One balloon dreidel
Pikachu balloon hat