Sethbling is an absolute wizard.
Coloured slimeblocks are my new favourite blocks in the game, and they aren't even in the game. Sethbling has made me a data pack that puts fully functional coloured slimeblocks and it works perfectly!

Check out his video here (As well as get a download link to play with these yourselves!):
https://www.youtube.com/watch?v=K5Ejwxlj0AQ&feature=youtu.be

Filming channel: https://www.youtube.com/user/ThatMumboJumbo2
Instagram: https://www.instagram.com/officialmumbo/
Twitter: https://twitter.com/ThatMumboJumbo