i have made one like a vocano but way more easier..... heat gun,heat gun reducer nozzle to fit into glass tube, pvc valve, glass tube or metal tube that will fit the top of the pvc valve and then a turkey oven bag and a rubber band.
very simple but to elalborate. heat gun blows in reducer nozzle. air goes down to glass tube( better) or metal tube then past the pvc valve that can be opened or closed then to the oven bag attached to the bottom of pvc valve. i use 2 tubes where there is a tube before the pvc and after, then to the oven bag. from what I heard the element in the soldering iron isn't the best for you so air convection is better. do add a screen after the first tube before the pvc to hold your spice.