hydraulic excavator toys made with syringes

Applications of syringes for DIY builds are limited. There are some legitimate fluid handling applications. However, used, they're medical waste, and probably shouldn't even be touched.

But kids go crazy over heavy equipment, and this is a good option for a science experiment or just a cool toy. Videos indicate that syringe-operated hydraulic models seem to be trendy now as projects for mechanical engineering students.

This one is from what I believe is a YouTube channel run by a young man with projects like homemade cotton candy makers, slingshots, candy dispensers, etc.

https://www.youtube.com/watch?v=g8suRwUP__g

I used to buy ground glass syringes of 10 and 100 ml sizes and connect them together with mineral oil as a hydraulic oil. Then drove the 10 ml with a 0.0001" resolution micrometer head and was able to end up with 10 x reduced motion on the 100 ml syringe. This was used to move an electrode in a medical research application. Quite reliable although one had to carefully select the syringes with regard to leakage.

I've recently collected a large number of 10 ml syringes which just had saline water for flushing IV lines. They are completely safe.

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