A Reel Cool Summer by Martha Rodriguez.
The illustrations in this book are great. They are very rich, interesting, and full of color.
It's a cute story of two brothers and their sister who use an old video camera to make a movie. After all, it's a super hot day and they are bored. It's a day that is like lava and the mall! Their guinea pigs star as aliens in this story.
They then enter the movie in the library's movie contest and they win a mystery prize, which is absolutely perfect for the lava mall days of summer!
This is obviously a children's picture book, but it's cute, guinea pig themed, and only 99 cents on Kindle. You can read a preview here: