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).