TPG is the acronym for a 3D imaging gas chamber with GEM amplification, hexaboard read-out and FADC electronics. We have constructed a TPG-head with three GEM foils (30 cm diameter) and a read-out board (30 cm diameter active surface) covered with 710,000 hexagonal pads of 300μm size. Aligned pads are connected in parallel to one strip out of three sets of 576 parallel strips (500μm pitch). The three sets of strips run at 120∘120∘ from each other and at three different depths inside the hexaboard multilayer structure. Each strip is read out by FADC electronics. The TPG-head is under initial test in a small container with a drift volume 33 mm long and of 30 cm diameter. A 150 cm long drift volume inside a 0.7 T solenoidal magnetic field has been prepared by using HARP-TPC instrumentation as test bed.