SOLVED. children's book about triangles who collect stuff [s]

[A]

probably published between 1950-1980, children's book, triangles who build their house out of trash that they collect and fill their house with said stuff...can't remember the ending.

[Antonomasia]

Hopefully this isn't too annoying but it's definitely not a misremembering of Wombles books is it?

(Publication date, character behaviour match and their heads could be described as triangular...)

[Cheryl]

The Wombles

[A]

no, thats not it,thanks

[Tab]

Were the characters triangles or were they creatures shaped like triangles?

[Feliks]

was it, Trillions?

[A]

Thanks for all your input - after kind of giving up hope, I was at my mother-in-law's house recently, and she was giving away some boxes of old children's books - and I found this book! It's "The Block Book", by Susan Arkin Couture, and the characters were actually cubes, but they did have a friend who was a triangle which is why I got a bit confused.