This "handheld printer" was made from a repurposed HJ inkject cartridge — because it's handheld, it can print on odd surfaces like balloons:
The fact that it was built from parts readily lying around makes, for example, that MOSFET T1 is a rather strange type. In principle any P-channel MOSFET can be used for this, as long as it can cope with the peak current of about half an amp. The coil L1 does not have a critical value either. The author's coil comes from a backlight-inverter, but any slightly hefty coil will do. If the 20-V power supply is actually in the vicinity of 20 V, then all is well.
(via Gizmodo)
