CHAINSAW MAN! (and Pochita): Fully Operational Helmet, Arm Blades, Sound and Motion

Chainsaw Man is a surreal character, born from an equally bizarre Manga. I first experienced this character as a text message attachment from my son, and from that point forward I have been sketching, bending foam, and working late into the night (manipulating The Matrix) within TinkerCad to bring a character with a chainsaw bursting from his forehead into our reality — and his little dog Pochita too. These two characters took more than a few iterations each to make them practical and reliable. There are many tutorials online for Chainsaw Man Cosplay, and I have included their versions (as web-links) because the artists/engineers that offered them were truly genius. 

My interpretation Chainsaw Man and Pochita is the following: individual sounds for Pochita’s chainsaw, Chainsaw Man’s Helmet and arms, and both the props and costume are designed to survive beyond Halloween, and work 10/10 times.

I printed this helmet in pieces:

1. The rear section (as a whole) which took 3 full days to print (.2 standard thickness).
2. The face shield in two sections, also 3 days to print (.2 standard thickness).
3. The teeth and jaw (with the teeth within the jaw, not printed separately) 3 days to print (.2 standard thickness).
4. The top of the helmet - again 3 full days to print (.2 standard thickness).

I could have reduced the print time by printing in “draft” (.28), but given the time constraints of the build I did not want to risk both PLA and overall time on sanding and puttying the final product.

I also used nearly three 2.2 Kilogram rolls of PLA for the helmet. It is rather thick, which is how I was able to drive one inch drywall screws into to it to secure heavier attachments.

I combined the best of many genius interpretations of this helmet that I found both online and in Thingiverse. The entirety of my version is linked within Tinkercad - where I separated the pieces for smaller bed 3D printers, and assembled them in larger sections for larger bed printers.

1. Prime all of the pieces of the helmet in two coats of Rust-Oleum glossy white paint (outdoors, with a respirator on, and well away from everyone).
2. The face shield, and the jaw are to be painted orange, also with Rust-Oleum glossy paint (orange). Use the blue painter’s tape to cover the white teeth prior to painting.
3. Two-to-three coats of paint on all of the pieces should suffice. Let the items off-gas their paint smell for at least three days before wearing.
4. I used gel Krazy-glue to adhere the heavy top half to the rear/bottom. I recommend blue taping both sections together and letting them sit for at least 24 hours. Krazy-glue loves to instantly stick to your fingers, but takes hours to join what you really want to glue.

Picture Montage A.

1. First remove the chainsaw blade mechanism from the prop chainsaw. Be careful of the wires from the circuit board to the activation switch and to the speaker as they are rather thin, and were not meant to be moved.
2. Bend your 3”X4” brackets in a vice, with vice grips. Look to the measurements in the photo - 2” X 1” X4”. This will then be mounted on the face of the helmet. Use the 1” dry wall screws and a bead of hot glue beneath the bracket as well. These brackets will hold the chainsaw blade in place. Or you can skip the metal-working and wedge (and hot glue) the blade in with 1” thick EVA foam. I would also drive 1 1/2” inch self-tapping screws through the foam into the non-moving parts of the blade.
3. Mount your battery pack next to the speaker on the top of the helmet. No one wants to see random wires protruding from your helmet. Run the switch wire inside the helmet (and cover it with blue tape) and then to the SPST push button switch that you drilled into the chin of the jaw (which is also a 1” piece of EVA foam - which you secured into the jaw bone).

Picture Montage B:

1. Hot glue the LED puck lights to the right and left temples of the forehead.
2. you now have to place at least two rubber bands on each of the jaw anchors, otherwise the jaw will just hang open.
3. Place the painted face shield over the electronics and you are done!

*** PRINT YOUR GEARS AND CHAINS NOW! This process will take at least four days at .2 mm. You will need 12 feet of chain to wrap around both arms. ***

Picture montage A:

1. I tried to build this version, as instructed, from this creator, but failed miserably to get the saws to run reliably. I do not blame the inventor, the fault lay with me. this version is also much lighter than my version.

Picture montage B:

1. Let’s cut some 1/2” thick cardboard! I measured four pieces and cut them 6” wide and 27” long.
2. I then roughly traced my forearm into the bottom third of the arm blade. I cut out my arm tracing, and then used this as a stencil to cut the other three blades.
3. I hot glued 1” EVA foam as a spacer to keep the spinning gears from rubbing against the cardboard, and to also offer a guide for the chains to run.

Picture montage C:

1. Mount the larger free-spinning gear on either a wooden dowel or a 2 1/2” bolt.
2. Mount the four guiding gears the same way.
3. Lay your 3D printed chain and be sure to have some slack, but not too much. Too tight and the chain will stretch or pop, and too loose it will fall off of the gears.
4. AFTER you find the right length mark and mount your free-spinning gear and your motorized gear.
5. take it for a test run before you close up the arm blade.

Picture montage D:

1. I am still debating if I should cover the electronics or not; leaving the technology exposed gives it a Steam-Punk vibe.
2. Please make note that the drill motors are hot glued and mounted to the cardboard through 1” EVA foam squares.

Picture montage E:

1. Versions 2 and 3 of my blade models. Both working 10/10 times, but Version 3 is better balanced.

Picture F:

1. This is the placement of the electronics for the arm blades.
2. The large 4 ohm speaker sits in and at the top of the blade (remember there’s 1 inch gap).
3. The electronics are: the 50 watt amp (and a 9volt power supply, the MP3 triggered audio, the LIPO battery for the drill motor, and the battery pack for the MP3 trigger.
4. There is a 12v rocker switch mounted where your thumb will sit for the chainsaw blade, and a small SPST push button switch just above it to trigger the MP3 audio.
5. Each saw has its own signature chainsaw revving sound. I wanted all three to be unique.
6. All versions were heavy, but once you strap the Velcro to your forearm it feels like your arm, and the weight transfers naturally to your shoulder.
7. Paint the cardboard blades with gesso mixed with grey paint. At least two coats, and then smatter it with dark red paint. The gesso also toughens/hardens the cardboard and keeps it rigid.
8. Cut out small isosceles triangles out of foam science fair boards for the teeth of the blades, and then hot glue them on one at a time.

NOTE: Pochita was printed in three sections to allow for the proper placement of the electronics.

He was glued with gel Krazy-glue, taped, and let to set for 24 hours - prior to implanting the electronics and the saw blade.

A. Jump the existing switch in the circuit board to an external SPST push button switch the you will later mount to the handle.

B. Hollow out the base of levels 1 and 2 (for the electronics, and two battery packs). I used a multi-tool for this, and was thoroughly impressed on how well it cut through the PLA plastic. I cut a square 3.5” X 3.5”. This will later both serve as the cover for the internal electronics and the home for the speaker that will be cut into this lid.

C. Krazy-glue the three completed sections together; tape it and let it sit for at least 12 hours.

D.

1. Build your face chainsaw from plexiglass-glass (or cardboard) and follow the same design as the larger arm blades. This time you can use the smaller RC motors. You will have to print two additonal large gears, and more chain for this.
2. I removed the printed handle and melted in two hollow aluminum bars, which were then wrapped in blue tape prior to painting orange. The chainsaw switch will sit on top of the handle, and the push button switch (for the sound trigger) can either sit as they do just above that switch, or like mine, beneath the handle - where your index finger sits.

E. Bottom view of Pochita.