With Israel blocking imports of building materials, those rebuilding in Gaza are recycling ruins to make new homesIt is difficult to see through the dust inside the cramped, low-roofed tent on the eastern edge of Khan Younis. Ibrahim al-Aloul works alongside four others, with a piece of fabric tied over his mouth and nose as his only shield against the toxic grey powder as he sifts and grinds.Outside, a skinny donkey waits with a cart to carry t…