Some people like the smell of solder but it's usually a good idea to avoid breathing it if you can, this will help you do so.Besides the printed parts you'll need a fan, filters and a few screws and nuts. I designed this to use a standard 120mm PC fan which I think most people have laying around. The filters I used had these dimensions: 130 x 130 x 10 mm and I stacked three of them together. I bought my carbon filters at Conrad, but I'm sure you can find them elsewhere as well. . The cross thing is optional and can be used to prevent the filters from moving back too far. I found I didn't need it though. . The front of the head has a lip. I included this in case you wanted to design something to go infront of the filters, for whatever reason. I first thought about attaching a flexible hose to the front but decided against it (didn't need it really).