The shrinkage kinetics of copper powder porous samples under spark-plasma sinter-forging conditions with and without the electric current passing directly through the specimens is investigated. An innovative tooling setup enabling clear comparative experiments on current-assisted and current-insulated spark-plasma sintering experiments under the same temperature and pressure conditions is developed. The created special spark-plasma sintering tooling allows the direct temperature control on a free lateral surface of a powder sample as well as the in-situ measurement of its radius and height during spark-plasma sinter-forging. The conducted experimental work contributes to the fundamental understanding of the physical phenomena underlying the technology of spark-plasma sintering.