New answers tagged materials
I would use a hydraulic, similar to what is found on a door. One like the one linked below has a small button you push to set it, and then to release you just relieve the pressure from the hydraulic and it will come down.. Amazon - Hardware Door Closer Hydraulic
As an alternative, you could consider what I've done. My desk at the office is electric (I found a good source for electric desks at economical prices and we have several of them). But at home, I raised my entire desk up on blocks so it is at standing height, then got a "drafting stool" style of chair--basically an office chair with a longer gas tube and a ...
The device you're describing, sounds like a four-bar linkage. Not sure if you'll be able to find one available that suits your needs, or if you'll have to manufacture it yourself, or if it's even the best design for what you're trying to accomplish. But hopefully that will help you find what you're looking for.
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