I used a soldering iron Parkside (cheap from Lidl 12 Euro) with adjustable temperature 48Watt. The second is a soldering iron Lotring 30 Watt (Gamma 5 Euro) to start up the heating the first 15 minutes. Tube 320 mm length 21,5/16,2 mm diameter. Hopper Thing 152380. Use a copper wire and a hose clamp for assembly. Then isolate. Temperature test results. time 48w 30w temp. on top drill & temp. at hopper 0 0 0 20,6 20,1 5 x5 x 43,0 21,4 10 x5 x 130,5 22,7 15 x5 x 195,3 30,5 20 x5 0 204 45,3 25 x5 0 208 51,2 30 x5 0 213 50,7 35 x4 0 192,5 59,5 40 x4 0 192,5 59,5 45 x4,5 0 191,8 60 50 x5 0 198,7 60,2 55 x5 0 208 60,3 60 x5 0 215 60,2 120 x4,7 0 201 61,7 minutes x=on 0=off degree Celcius. Adjust the soldering iron (48 Watt) to 4,7 and the themperature will stay at 200 degree Celcius Next step is testing with granulate. Is there a cheap granulate adress somewere in the Netherlands? Thank you! See also thing http://www.thingiverse.com/thing:250594 Tunnelplan.nl