I had some 15mm thick material laying around and decided to give it a go. It came out a bit too wobbly (even tough I reinforced the legs with slats). But compared to the weight of the table, it’s OK and well suited for placing a laptop on it.
Tape a brick to the bottom of it.
I don’t get what you mean…
May have misunderstood. Thought you needed more weight.
OK, I see. I don’t think it’s a question of weight. The whole object is not stiff enough.