Those who use an office chair know that over time the gas lift fails and begins to fall under the weight of the seated person. At the same time, the function of raising / lowering, as a rule, no one especially uses. Played on a new chair a couple of times, then set the desired height and forgot. With this in mind, the master offers such a solution as locking the gas lift in one position. To lock it, he uses a part printed on a 3D printer.
You can download the file for printing here.