For my 3D printer I build a housing with the IKEA-LACK tables. They actually stand very straight on the floor when you screw on your legs properly. Unfortunately, the exact spot of the floor where I wanted to place the tables was uneven. I have therefore designed these adjustable feet in two variants.

Foot-Base
------------

This is the height-adjustable foot. I chose an M4 screw for my design because I had it in stock. It is more than sufficient in terms of stability, but I have to admit that it looks a little strange.

Additional parts:
4 pcs. hexagon screw M4x30 (or longer)
4 pcs. Nut M4

Table-Support_Var1
-----------------------

The first variant of the table support encloses the leg from all sides. A hole must be drilled in the middle of the leg so that the M4 screw of the base part has room for movement. If you still want to attach the parts to the leg, the screw holes should also be predrilled.

Additional parts:
4 pcs. Nut M4
8 pcs. countersunk wood screws (optional)

Table-Support_Var2
------------------------

The second variant of the table top requires more effort, but is almost invisible and in my opinion more appealing. You have to hollow out the table leg first, this is usually relatively simple, as the chipboards used are only 1cm - 1.5cm thick and quite crumbly. If you are unlucky, however, a 3.5cm plate of more stable material is glued in.
I think that the effort is well worth it and the result speaks for itself.

Additional parts:
4 pcs. Nut M4