I will tell you how I built a desktop computer using the motherboard from an old laptop that had a cracked LCD and a broken hard drive. I used Acrylic Alumina thermal adhesive to paste a big piece of aluminum on top of the CPU. It is actually glued on top of the heat pipe that is cooling the CPU.
I used two aluminum plates about two millimeters thick and in between these two plates, I put the motherboard from the old laptop. I used some standoffs, 6.5 millimeter and 18 millimeter standoffs to keep the plates at a certain distance from the bottom and the top of the motherboard.
