A tutorial that shows how to simulate a caustic balloon effect can be found below.

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Industry expert Arvid Schneider shares his knowledge and expertise on Shading and Lighting.

https://www.udemy.com/arnold-fundamentals/?couponCode=YOUTUBE-SUBS-SPECIAL

https://cgbookcase.com/

http://on-demand.gputechconf.com/siggraph/2018/video/sig1812-4-adrien-herubal-arnold-on-the-gpu.html

https://antongorlin.com/blog/photography-composition-definitive-guide/

Another (more advanced) tutorial that covers how to create a caustic effect (swimming pool) using the Cell Noise shader. Many thanks to Slava Sych for this tutorial.

Tutorials here:

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https://www.artstation.com/artwork/ErW5v

Some recent Lego renderings. More here.