Circular saws are well-tested and efficient tools when it comes to cutting things. The saw has a voltage of 11 volts and isn't all too heavy at 1.6 kg.
From Amazon
Makita Circular Saw, Blue, 33.3 x 19.1 x 18.5 cm
Conrad Electronic
Makita Cordless handheld circular saw w/o battery 12 V
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