This Sentence Makes Zero Sense

Hi,
New here. I am currently reading this story for class about a boy and his dog, and I came across this sentence that makes no sense to me:
僕はエルフの暖かいお腹をいつも枕にするのが好きだった。 (Elf is the name of the dog, by the way.)
I know basically what the sentence is saying. I just don't know how to put it in English.
Is he saying "I always like Elf's warm stomach, it's like a pillow"?
or "I like doing Elf's warm stomach as a pillow"?

I know I'm probably making this harder than it is, but I really don't understand...

XをYにする means "make X so that it is Y". I.e.: "I always liked to make Elf's warm belly into a pillow", or more naturally, "Use Elf's belly as a pillow".

It also works with adverbs, e.g.: 静かにしてください. "Please make it quiet" i.e. "Please be quiet". There is a special case if こと is used: もっと勉強することにしました could be awkwardly translated to "I made it so that I will study more", but a better translation is "I decided to study more".

lanthas said:

XをYにする means "make X so that it is Y". I.e.: "I always liked to make Elf's warm belly into a pillow", or more naturally, "Use Elf's belly as a pillow".

It also works with adverbs, e.g.: 静かにしてください. "Please make it quiet" i.e. "Please be quiet".

Click to expand...

THANK YOU! I knew it was saying something like that, I just didn't know what! This has been bugging me for like two hours, so thank you thank you!