When dry, remove the legs from the offcut. Use 20mm button-head screws to secure the legs under the desktop, flush with the edges to allow for the cable duct opening. Attach the painted downpipe clip using 20mm screws and position the planter. To prevent the desk from moving, at the back of the desk, position two 75mm x 50mm angle brackets underneath with the 50mm side of the angle against the wall then transfer the position of the screws onto the wall. Use anchors suited to your wall type to secure the brackets, then position the desk over the brackets and secure underneath with 20mm pan head screws.
Position timber offcuts under the desk while drilling to avoid damaging your work surface.