Wednesday, July 21, 2010

Harkonnen Cannon Tutorial


The harkonnen cannon is a weapon the character Seras Victoria carries in the anime Hellsing. This tutorial creates a cannon that is 6' 3” long. Otakon, the first convention I am going to, has a limit of 6' 6” for any weapons, so this should fall well below that. The directions that follow make exactly what I made. There are certainly some changes I would recommend. Firstly, PVC pipe is fairly heavy. I would recommend trying to use ABS piping instead, as I've heard it is three times lighter. I have not used ABS piping before, so will not attempt to instruct on how to use it. Also note that this design has a joint about halfway along the barrel that can be unscrewed. This is to allow for easy transportation in a car. Note: In this tutorial “front” refers to where the bullet would come out of the barrel, “top” is where you would aim along, “bottom” is the base of the handle grip, and “back” is the part that rests against your shoulder.


Main barrel:

  • 1x 2” PVC or ABS piping (10 ft)
  • 1x 3” PVC or ABS piping (3 ft)
  • 2x 2 to 3” PVC external adapter
  • 3x 3” PVC coupler
  • 1x 2 to 3” PVC external adapter
  • 2x 2” 45 degree joints
  • 1x male ABS 3” screw joint
  • 1x female ABS 3” screw joint

Handle region:

  • 2x 18” drainpipe (large size)
  • 1x sheet of dense pink foam
  • 1x roll of electrical tape


  • 1” PVC pipe (about 2 ft)
  • Scrap pink foam from earlier
  • Electrical tape from earlier
  • 2x bolts with nuts
  • 1x Small piece of wood
  • 1x General hinge


  • 1 can Black metallic textured paint
  • 1 bottle white paint (I used tempra, but any should work)
  • 1 paintbrush
  • 2 screws with large round heads for optional guitar strap
  • PVC primer and PVC cement
  • Wood screws for hinge (usually 4) and attaching drainpipe (I used 3)
  • 5 minute epoxy
  • Marker
  • Glue stick
  • Printer (to print out stencil for lettering)

Tools you will need or want:

  • Hand saw (or band saw/table saw if you prefer)
  • Vice (if using hand saw)
  • Exacto knife or razor blade
  • Drill and drill bits
  • Pliers (for bending the drainpipe)
  • Tape Measure
  • File
  • Tin Snips or other tool to cut the drainpipe metal
  • Ruler

STEP 1: Cut PVC lengths
Need: Hand saw, vice, 2” and 3” PVC pipe

Remember to add the depth of the fitting that will be on either end to each of the below measurements, as I am measuring them again after assembly, so cannot include those.

2” PVC:
26” piece
2+” (for the stock to attach to)
3” PVC
14” piece
Two 1/2” pieces

STEP 2: Assemble PVC fittings WITHOUT using PVC cement
Need: Cut PVC from step 1 and PVC fittings

Order from left to right with the handle on the right side:
3 to 2” external coupler
26” long 2” PVC pipe
2 to 3” external coupler
female ABS adapter (threads on inside)
male ABS adapter (threads on outside)
1/2” long 3” PVC pipe
3” coupler
14” long 3” PVC pipe
3” coupler
1/2” long 3” PVC pipe
3” coupler
Internal 3 to 2” coupler
45 degree 2” PVC bend (facing downward)
45 degree 2” PVC bend (facing upward)
2+” long of 2” PVC pipe

STEP 3: Cut and bend the drainpipe
Need: Pliers, Tin Snips, both drainpipe sections, assembled barrel for measuring

First slide the two pieces of drainpipe together (they will slide inside each other when the right ends are put together).

The top of the drainpipe will sit flat against the 3” PVC pipe, but the coupling are in the way. So, cut a slit across the top of the drainpipe at the seam of the coupler and the pipe. Do the same on the other side of the coupler. Now use the pliers or just your hands to press the part of the drainpipe down that will be touching the coupler. It should indent enough that the drainpipe is touching the barrel both along the coupler and along the pipe. Sorry no pictures, it's almost impossible to see now that it's assembled!

Now on the front end, you will need to cut a slit down each corner. Then bend in the two short tabs, and finally the two long tabs. For the back end, only cut the bottom two corners. Now bend in the short tab like before, but only bend in the corners so that there's more of an angle. On the other short face of this end, cut a slit down the middle of the face and bend them upward so they seem to extend the two longer sides. These tabs will eventually be screwed to the barrel.

Front end:
Back end:

STEP 4: Carve the Handle and trigger area
Need: Razor blade, hand saw, ruler, marker, foam

This was mostly done to fit. I made it narrow enough to fit my hand around while still trying to keep the right proportions. The trigger was also made from foam and glued with epoxy in place. Make sure that you leave the part above the trigger hole solid so that when you go to glue the handle in place, there will be a lot of surface area touching the drainpipe. My measurements are 2-2.5” from front to back on the grip and maybe 2” wide. The diagonal from the base of the grip (including the jutting out part right at the bottom) to the top of the trigger hole is 6”. The trigger hole itself is 2.75” from front to back and 1.25” from top to bottom at its widest part.

STEP 5: Cover the foam handle with electrical tape
Need: electrical tape

Wrap the tape at a slight angle around the handle until all the visible parts are covered. If you do not, then when you paint the foam it will have a much different texture than the rest of the gun.

STEP 6: Attach the handle to the drainpipe
Need: 5-minute epoxy or other good glue, drainpipe, Tin Snips

Cut out a rectangle in the bottom of the drainpipe that the handle will fit into. Also cut a curve along the two sides so that you can see through the trigger hole. The midline of the trigger hole (from top to bottom) should be in line with the bottom edge of the drainpipe. It will take some wiggling to get the handle into the hole. Glue the foam to the inside of the drainpipe and glue in two small foam spacers between the handle and the sides of the drainpipe.

STEP 7: Cut foam filler block and cover in tape
Need: Razor blade, hand saw, ruler, marker, foam

I cut a small rectangle of foam, just enough to cap the end of the drainpipe. It's snug enough I didn't need to glue it, but a dab of epoxy should hold it in place if it's loose.

STEP 8: Carve foam stock and cover in tape
Need: Razor blade, hand saw, ruler, marker, foam, electrical tape

Make sure it is wide enough to have the 2” pipe inside it. Besides that it's mostly done to taste. Mine measures 5” from front to back, 6” from top to bottom, and 4” wide at the back (where it rests against your shoulder).

STEP 9: Make legs
Need: hand saw, marker, drill, hinge & screws for it, block of wood, 2 bolts with nuts, vice

The small wooden block should be about 4”x1”x3/4”(or less). Cut two lengths of 1” PVC. I cut my legs 9” long. You will need to cut a slot on one end of each of the PVC pipes. The slot needs to be the width of the smallest dimension of the piece of wood. Use a drill bit that is the size of the bolts you are using plus the threading on the bolt. Drill through the remaining tabs of PVC and the block of wood. Slide the bolt in and tighten the nut such that you can still move the PVC, but that it will not swing freely. Do the same for the other PVC pipe on the other end of the piece of wood.

I used some scrap pieces of foam to wrap around the bottom part of the legs to make them wider. I held the foam on with electrical tape. Again, cover all the foam with the electrical tape.

Attach the hinge to the opposite side of where the legs extend from. Make sure that it's in a direction that will work with the range of motion of your hinge. Later the other end of the hinge will be attached to the barrel.

STEP 10: Disassemble and paint
Need: Paint, newspapers?, good ventilation

As you disassemble, use painter's tape or masking tape to tape off at least the last inch of the PVC pipes and an inch of the inside of the fittings. This way they will not get paint on them that will interfere with bonding the parts later.

Also make sure to get inside of the 3” part of the coupler that will be the front of the barrel of the gun.

STEP 11: Bond the PVC pieces together
Need: PVC parts, PVC primer (purple), PVC cement

If you have never bonded PVC together or even if you have, carefully read the directions on both bottles.

WARNING – PVC primer stains everything horribly, including hands. Please wear gloves and go somewhere ventilated as the fumes are also very potent.

The first thing you are going to do is put on the PVC primer. It does not take a lot and is very liquidy, so wipe off most of what's on the brush on the inside edge of the can before you brush it onto the PVC. Coat both the outer edge of PVC pipe and the inner edge of the PVC fitting (only exception is the internal 2 to 3” adapter where you coat the inside of the pipe and outside of the fitting). The purple primer should dry in 30 seconds or so. It doesn't really matter, but I'd recommend doing all the priming at once just so you don't have to keep switching between bottles.

Now you're ready for the PVC cement. Read the directions on the bottle. This is the tricky part because once you have the PVC cement on the pipe, you only have maybe a 10 second window to get the pipe in place how you want it to be. Double check that the piece is the right one and that it is oriented the way you want it (especially for the 45 degree bend pieces). Try not to put too much cement on or it will ooze out of the joint when you put them together. You just want a thin even coating. Once coated, press the pipe firmly in the fitting and hold for a minute or so. This will prevent the cement from pushing the pipe out a little and not making a straight bond.

STEP 12: Attach the drainpipe
Need: drill, drainpipe, assembled barrel, screws, pliers?

The drainpipe should still fit well against the barrel because of the slots you cut before to make room for the fittings. Gently unfold the flaps at the closed end of the drainpipe (side towards the front). Use the drill to pre-drill a hole that is the size of the screw without the threads. Then use the drill to put a screw where you already drilled. Now refold the flaps.

The two flaps that are on either side of the gun near where the handle is will be the next place to screw. One screw (also pre-drilled) into each flap should hold it tightly against the PVC. I screwed mine through the flaps directly into the front-most 45 degree PVC joint.

STEP 13: Attach the legs
Need: drill, assembled barrel, assembled legs, 2 screws

Find how far you would like the legs to be in front of the drainpipe. Mine is attached to the 2 to 3” coupler that is right in front of the screw joint in the barrel. Set the free end of the hinge down where you'd like it to be. Pre-drill two holes through the holes in the hinge. Be sure to drill straight down, not towards the center of the PVC. This is important because the hinge is flat and we're attaching it to a round surface. When the screws are tight, there will still be a gap. In order to have the screw heads flush against the hinge, they must be pointing straight downward. Now start to drill one of the screws. Just get it started, then do the next screw. Switch between the two, tightening first one then the other so that the hinge does not get pulled to one side or the other.

STEP 14: Attach the stock
Need: Foam stock, assembled barrel, epoxy

Mix some epoxy and hold or tape the stock in place on the end of the 2” PVC while the epoxy dries. This will not be an incredibly firm joint, so you will need to be careful with it in the future.

STEP 15: Paint detail work
Need: Paper, scissors, printer, white paint, paintbrush, glue stick

I used Microsoft Word to make the stencil. I used “Stencil” font, not surprisingly. To make scalable words, I inserted the text as WordArt. There are different words on the gun if you want to make the English or Japanese version. I used “HARKONNEN CANNON” and “30MM”. The “MM” was in smaller font.

Once you print out the lettering with the right size, use scissors to cut out the inside of the letters. I cut straight in from the bottom of each letter and then taped over the slit I had used to cut into the letter with scotch tape. Be patient, this part takes a while.

When done cutting out the letters, get the glue stick. Determine where you want the lettering to start, then glue the paper in place on the drainpipe. Be sure to smooth it out and don't be afraid to use a generous amount of glue. The goal is to have all the edges of the letters firmly attached to the drainpipe.

Now dip the brush into the white paint and carefully dab it on over the letters. You will need to put it on pretty thick in order to get a pure white. When all the letters are covered, gently pull off the piece of paper. I discovered that some of the paint smeared a tiny bit between the letters, so when the paper was off, I got a toothpick and carefully removed any paint that was unwanted.

Let the paint dry thoroughly so it won't smear.

OPTIONAL STEP 16: Attach screws for strap
Need: Drill, two screws, guitar strap

Use two screws with large heads. But check first with your guitar strap to make sure that you can put the strap on over the heads and that it will not cut into the leather or plastic. Next pick a location to put the two screws. I put one in the diagonal edge on the same 2 to 3” coupler I attached the legs to. The other was near the back of the first 45 degree angle joint. They are probably pretty large, so go ahead and pre-drill with the size of the screw minus the size of the threads. Screw them in, leaving about a quarter inch of space for the strap to sit in.

You're all done!


  1. how much does it cost for all the material...because thats a lot of stuff...

  2. That's a lot of detail! Thanks so much for posting this up! I'm excited to use it in the future when I do my Seras cosplay.