Print settings, section breakdown, assembly, and LED eye wiring — from someone who's actually done it on a stock Ender 3.
This is the video that started the whole suit project. Watch the helmet come together from raw filament, then read the guide below for the details.
These are the exact settings used for the IronBuilds MK85 helmet. They work on any mid-range FDM printer — no tuning needed if you're already printing reliably.
You don't need a fancy printer for this. The IronBuilds helmet was printed entirely on a Creality Ender 3 — one of the most common hobbyist printers out there. If you've already printed a few test pieces successfully, you have everything you need.
PLA is the right call for the helmet. It's easy to print at standard temperatures (200°C nozzle, 60°C bed), produces clean surfaces, sands down nicely when you want to smooth the layer lines, and takes paint well when you eventually get to that stage. Don't bother with PETG or ABS for the helmet — you'd just be making life harder for no real benefit.
Grey filament is worth using if you can. The raw grey PLA looks great on camera before any finishing, and it's a neutral base for whatever colour you end up painting. Most MK85 builds go with red and gold eventually, but leaving it raw grey while the build is in progress looks intentional rather than unfinished.
The MK85 helmet is far too large to print as a single piece on a standard 220×220mm build plate. Good STL files already come pre-split — here's how the sections divide up.
The MK85 files used in this build are sourced from Printables and Thingiverse. Search for "Iron Man MK85 helmet wearable" and look for versions that are already split for FDM printing — you'll see preview images showing all the separate pieces laid flat.
Check the comments on whatever files you download. The community is good at flagging versions with fit issues or thin walls. A file with 50+ makes and lots of comments is a safe bet.
Print the face plate sections first so you can check the eye gaps fit your chosen LED modules early. There's nothing worse than finishing the whole helmet and then discovering your LED modules are 2mm too wide. The eye openings can usually be cleaned up with a small file if needed, but it's easier to account for it at the start.
Tip: Print a small test section first — a 50mm slice of the cheek piece — before committing to a full 10-hour run. Check layer adhesion, wall thickness, and that the scaling is right for your head.
The assembly process is straightforward. Dry-fit everything first, then work section by section with superglue and filler on the seams.
Before any glue, hold all six pieces together and check the fit. The sections should align cleanly. If there are small gaps, mark them — you'll fill those later. This is also when you check whether your head actually fits inside. If it's too tight, scale up by 2–3% and reprint the worst offenders.
Run 120-grit sandpaper across every joining face to remove any elephant foot or slight warping. Flat surfaces = strong joints. This takes five minutes and makes a real difference to the final look.
Use cyanoacrylate (superglue) — the gel type is easier to control than the thin liquid. Join the two face plate halves first, then attach the crown, then bring in the back panels. Working in pairs means you can hold each joint for 60 seconds without juggling the whole helmet.
Once the glue has fully cured (give it an hour), apply lightweight body filler or Bondo to all the seams and let it dry. Sand back to a smooth surface with 180-grit, then 320-grit. The seams essentially disappear at this stage. This is optional if you're going for the raw unfinished look, but it's required before any painting.
Don't fill or close the eye gaps. These are deliberately left open to accept LED modules. The MK85 eye shape is designed around LED lighting — closing them off would lose the most iconic detail of the whole helmet.
Important: Don't rush the glue curing time. Superglue on PLA bonds fast but the joint isn't at full strength for 10–15 minutes. If you're applying filler too soon, you can pop joints apart. Give it a proper hour before you stress any seams.
The eye glow is what makes the helmet recognisable. Two approaches — one plug-and-play, one custom with Arduino.
The eye gaps in the MK85 are designed to hold LED light sources. When they glow that cold blue-white, the whole helmet transforms. This is the electronics part most people ask about, so here's the complete breakdown.
The easiest route is a purpose-built Iron Man eye LED module. These come as a matched pair, pre-wired with a battery pack and a simple on/off switch. You slot them into the eye gaps, connect the battery, and they glow. No soldering, no coding, no wiring knowledge required.
They typically cost £8–15 on Amazon and produce a very clean, steady glow. If you just want the helmet to light up without any complexity, this is the right choice. You can always upgrade to Arduino later — the eye gaps stay the same size.
For a movie-accurate startup sequence — where the eyes flicker on and stabilise, or pulse gently — you need addressable LEDs and a microcontroller. WS2812B LED strips cut to size fit the eye gaps, and an Arduino Nano drives the animations. The code for a basic startup flicker effect is about 40 lines and is documented in the Electronics Guide.
This approach takes an evening to set up if you've never used Arduino before. The full guide covers the wiring, components, and code you need.
The full parts list with links and wiring instructions is on the Electronics Guide page.
Shorts: The video below shows the helmet eyes switched on for the first time. That reaction is exactly why this part of the build is worth doing properly.