I LOVE this shelf made of 2x4s. (See what I did there?) Which should have books on it amiright? You could do this quite easily with a mitre box (or even just a pencil) some screws and a hand saw. It would take much longer than using a jig saw but it can be done!
I wish I had a source for this but thanks to Pinterest, it has been lost. If anyone could give me a link I would greatly appreciate it. Thank you absolutely precious. Shelf is from The Old Mason Jar on Etsy which the owner is currently taking a break from.