DONT TAKE MY WORD FOR THIS< I DONT KNOW IF YOU ARE SUPPOSSED TO USE METAL OR PLASTIC, and i dont want anyone blowin themselves up...
Maybe a honey oil expert can come clarify for us....
ive done quite a few bho runs, the reason your not supposed to use plastic is because the butane strips layers of plastic from the inside of the tube and chemicals leach out into your oil, pvc pipe is the worst for this, the only metal that should be used realy is stainless steel, i did make a copper tube extractor once with drilled copper blanking caps at each and i noticed a copper taste to the oil. most grades of s/steel will not react with the butane, iv just got myself a honey bee extractor(see pic) its made of plastic but its not supposed react with the butane whatsoever, il post pics on another thread when i use it for the first time. another important point is to make dam sure your butane can carries a "near zero impurities" label (see pic), camping type butane, soldering iron butane and cheap butane lighter refills contain impurities that will not evaporate with the butane and will be left behind in the oil you smoke, camping butane often has extra odour added to it to make it more detectable in the event of a leak at the campsite, most of these impurities are harmfull to your health when smoked and are what most of the controversy surrounding bho are about, i also make hash similar to the "gumbo" method video after seeing a thread on another site donkeys years ago, but i freeze my trim over night before hand, whisk up my trim, pre-chilled water and ice in one bucket and have another bucket with a pair of tights stretched over the top. then i remove the ice and as much trim as i can by hand from my "mixing" bucket and pour the water through the tights into the other bucket then after its settled for 6hours i start ladeling off the water from the top, and i use a syringe to remove last remaining water, but definately the easiest method for a first time hash maker is the dry sift method, but the results are a lower grade as you always get some amount of plant matter in your hash........