From the armaments of shot down attack helicopters or from spent ordinance recovered at battle sites, find Depleted Uranium rounds .. acquire redundant 175 mm High Explosive artillery shells .. reduce the captured DU to swart with a lathe..
Remove the fuse and base plate from the shells and drill holes into the HE, in an argon purged environment to prevent the DU swart from spontaneously combusting, pack it into the drill holes then replace the base plate, fit the primer and detonator and voila a home made nuke .. reason the tremendous heat and pressure generated when the High Explosive detonates inside the artillery shell case, enriches the DU and precipitates a nuclear blast.