Handheld Water Pump

Buy a cheap irrigation water pump from Aliexpress, add four 18650 Li-ion batteries through a battery box, add a DC power jack, and add a switch, then you get your water pump. You will need to buy 10 mm inner diameter water tubes to connect these items together. There is no induction motor at the pump head and there is no need to prime this pump since this is a self sucking pump. You can also use this to suck the water tank dry even when water level is only a few mm deep.

This is printed with PETG. I tried PLA and the tube coupling nozzle easily cracked when the silicon rubber tube is pulled out. The advantage of PETG is it has very good layer to layer adhesion even when the wall thickness is only 1mm.