UPDATED COMBI-FLAMER
Well for those of you who have been following my SoB WiP thread, you should know I originally started building these combi-flamers for my Sisters of Battle. The first 'prototype' was pretty impressive, but I was never really completely satisfied with the overall look.. It wasnt quite " sisterly " enough for my taste. It was much to large and better suited for a space marine or something of the sort. With this in mind I recently set about making a NEW combi-flamer. The new look is much more compact and overall closer to the combi-flamers of SoB fluff.
If anyone is interested, heres the link to my WiP thread:
ID is Tired of Playing with Naked Sisters of Battle!!!
As requested, I will be updating this Tut with instructions on how to construct both versions of my flamer toys. I hope you find these instructions helpful and easy to understand.
Enjoy! ~ID
Old Combi-Flamer:
The NEW Combi-Flamer:
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PART ONE: OLD COMBI-FLAMER
For my Sisters of Battle army I had decided to equip my Veteran Superiors with the elusive combi-flamer. I had searched high and low for this bit and soon realized how rare it actually was. I had found only one mini that actually had this item modeled onto it, unfortunatly for me the model had long since been retired and is no longer in production. So I set out to create my own...
After several prototypes and receiving the ' Drax/ Erus seal of approval ' along with many threats of ' stick beatings ', I decided to go on and start this tutorial. This is my first attempt at a " How to " so please bare with me, and I hope you find this little tut helpful.
Materials needed include :
- Space Marine Combi -Melta
- Catachan flamer
- copper wire
- brass modeling tubing
- modeling tube cutter
- clippers
- hobby knife
- pin vice with varius sized drill bits
- a magic marker, or sharpie pen
Lets get started...
Step 1 : Take your hobby knife and carefully remove the flamer head and gun barrels from the multi-melta.
DO NOT DAMAGE THE BOLTER BARREL, you'll need this later so be careful with this bit or you will be hard pressed to fabricate another. 
These are the parts you'll need to construct the combi-flamer. At this point you should take the bolter barrel and put it some place safe or you WILL misplace it as I did, things would be much easier if you didn't need to construct another barrel from scratch.
Step 2: We will be drilling pilot holes into our parts. This will make it easier to drill through with a larger bit later, and will overall insure accuracy.
Start first with the flamer head, we'll eventually need to drill all the way through, but don't do that just yet. Take your pin vice and a small drill bit and center yourself in the back of the flamer head and drill a few millimeters deep.
STOP!! Its very important that you do not attempt to drill all way through from one end. After you are a few millimeters deep, turn it around and drill the rest of the way through the FRONT of the flamer head. By drilling from both ends, you ensure a straight shot and won't risk drilling crooked.
Drill you next pilot hole into the body of the combi-melta. Center yourself just under the mid point of the front of the combi melta and drill in a few millimeters deep.
Step 3: Take your pin vice and a drill bit the same size as your brass tubing and drill all the way through the flamer head and a few millimeters into the combi-melta. Center yourself with your pilot holes and things should be a peice of cake.
Step 4: Dry fit everything together, and mark off where you plan to cut your tubing with your magic marker. You want something about the length of a normal SM flamer with a millimeter or two of tubing sticking out of the front of the flamer for form a nozzle.
Once you got your tubing marked, remove it from the combi-flamer and cut it with your tube cutter. The tube cutter for those of you who have never seen or used one, is basically a clamp with a small rotating blade which you tighten and twist around your tube or pipe.
DO NOT USE YOUR CLIPPERS, you'll only pinch the ends of the tubing and most likely damage your clippers. 
Step 5: Without gluing the tubing in place stick it in its appropriate hole in the combi-melta body. Use a drill the same size as your copper wire and drill a second hole a few millimeters deep just under it. Do the same to the back of the flamer head.
Continued Below: