Print with the tube where the powder comes out standing up. I recommend slicing this model with Simplify3D (or alternatively slic3r). The support structures needed are a bit complicated, because you need supports to support the bit that the funnel screws into, and also need supports for the arms that hold the "shaky bit" on, but you DO NOT want supports for the part where the powder comes out (this part should be done using bridging). Note that you might have to file down the part a bit if it comes into contact with the cartridge bracket, and you might need to use files to smooth out the bottom of the powder dispenser (which might be rough from the bridging).