L E G O Pneumatic Engines

[BronxFigs]

Over the last months, I have viewed many YOU-TUBE videos showing very clever, and also interesting compressed-air engine designs using "LEGO" building blocks and various other parts. The engine, especially some of the linkage configurations are fascinating to see work, and spin.

Question:
Are there dedicated web-sites that show drawings, diagrams, parts, etc to make these engines, and various other mechanical models?

Looking at some of these "LEGO" engine designs, I think that some may be adaptable to fabricating in metal, from bar-stock.

I'm hoping that there are some sites showing details.

Thanks for any help.

Frank