This video shows how to make a pair of stools from shock absorbers and coils springs. These coil springs were not under compression!!!
source/image: Eamon Walsh DIY
If you are attempting these and are not sure what you are doing make sure the springs are clamped as they maybe under compression and could cause serious injury when opening them.
Also before welding it to the base drill a small hole in the shock to release the gas inside. Although it should be inert gas it is wise to do so to stop the gas pressure building up from the heat of the welding.
The 50 mm x 25 mm box, flat steel and plastic inserts were all purchased from a hardware store and cost 25 Euro. The mdf for the seat was made from scraps I had and was glued together with gorilla wood glue.Always be careful using tools and machinery.