Today I finished making my adjustable height work bench with drill powered X-Carve CNC machine lift. I made the lift out of 2 trailer jacks flipped upside down connected by a 1/2″ rod.
Lift Mechanism Video – https://goo.gl/V2577x
I made the top shelf removable so when I need to use the CNC machine, I simply “lift” the middle shelf up to bench level. You could use the same design to build an adjustable height desk by removing the 4 outside legs. I still need to add a hand crank and adjustable feet.