I made another kind of height adjustable feet for IKEA KALLAX, this time lower but for heavier load, in my case a enforced Kallax with an aquarium on top. Just insert the big corner screw through the inner part of the foot and tighten it back in.

To make the thread extra robust, set perimeter to 5.
NO Print in Place, print the parts separated und turn the inner part upside down.

Base height: 12mm
Max height: 18mm