Adjustable foot for tray

I needed a tray to put my laptop laptop under. Unfortunately wood is not perfectly flat, and neither is the table. Here are some adjustable feet to resolve it.

Dimensions:
* base diameter: 40.6mm
* Foot diameter is 30mm.
* foot screw length: 5mm
* covered part of screw: 3mm

When adjusting both short sides, it can fix a 6mm difference.

Many foot sizes are included. But I doubt that a 100mm on very solid (I did build 40mm ones). The foot dimension means the total, including the base.