Google search plastic welding how to. Because the case plastic is so thin, a great deal of practice, and some tricks like copper tape temporarily placed on the good side, may be necessary to build up a stronger hinge mounting replacement boss structure without melting thru to the outside. It should look more like a sloping sides volcano rather than the original narrow based slender cylinder. The copper metallization EMI shielding stuff must be removed in the weld area, and for best strength absorbed water must be baked out of the case and the welding rods (chemically similar plastic scrap) before welding to avoid porous welds (from steam bubbles). Weld filler material can be cut from laptop and battery case scrap. Fumes are emitted during welding so good ventilation is advised. If a dialed down soldering iron is used, the plastic ruins the tip's ability to hold solder. There is an acid flux re-tinning process but subsequent removal of the flux residue by boiling water and mechanical scraping must be thorough before electronic soldering is resumed.