I've built particle board furniture for years and I can tell you that a screw in that board cannot hold much. Buy 4 metal legs which have at least 4 mounting holes each. Otherwise the only cheap option are 2 full panels left/right connected on the wall side of the desk with another panel 30-35 cm in height which you'll eventually have to screw it to the top part with metal brackets or if your brave/accurate enough, use wood pins Moreso, once you screw a screw in a particle board it is esential that you don't over screw it and break the thread. Multiple screwing in the same hole also weakens the bond. Do not use a guiding hole. Use screws as long as possible not to exit the other side. Particle board furniture can be sturdy too but it has limitations and it's highly recommended to deconstruct it if you plan to transport it to another location. If you want to make it extra sturdy and easy to break apart, mark the mounting plate holes of the metal legs and screw faucets in, the use metal screws to connect the legs. Hope this helps you and good luck