Have you ever wanted to decorate your builds with your very own Picasso or Van Gogh's, no worries, I'm not judging. I just wanted to let you know, that you totally can with the painting mod. You're welcome.
You can draw straight lines by holding down the shift key while painting.

LINKS:
Download Mod
Github repository
Forum Topic: Please visit this page to ask questions or request features.
P.S. You'll need the vector_extras mod to run this
TenPlus1 made an update to this that you can download here.

More mods by this modder

It doesn't look like I've reviewed any other mods by this author, feel free to suggest one.