Porosity in high pressure die casting (HPDC) castings caused by gas or shrinkage during solidification is mostly associated with a substantial reduction of mechanical properties. Particularly in complex castings with sudden wall thickness transitions, so-called hot-spots and micro porosity mainly occur in form of a spongy structure. The aim of this thesis is to develop a die, enabling to examine methods for local structural improvement by means of squeezing under near industrial conditions. Based on literature research, radioscopic and metallographic investigations were conducted on directly and indirectly squeezed industral parts, to examine micro structure, mechanical properties and porosity. The evaluation showed that a compensation of solidification-caused porosity/shrinkage by using a squeeze-pin and appropriate process parameter can be realized. Based on the industrial observation a HPDC testing die was designed, which is implemented as a double mould, wherein a casting sample and a reference casting can be manufactured. The geometry of the sample is constructed so that a hot-spot forms at a defined position, which can be purposefully manipulated by mechanical (and thermal) measures. After several optimization steps using numeric simulation models a prototype-die was manufactured. In a first test series the functionality of the die was confirmed.