Reactor Core trophy: painting a 3D print for the first time

Painting 3D prints? Me? I'm pretty handy with code. Paint, on the other hand... not so much. So naturally, when my local escape room announced a charity challenge, I put my hand up to make the trophy, and decided this would be the project where I finally learned to finish a print properly.

A trophy with a twist

The escape room was challenging local businesses to take on one of their games, a space-themed room. Whoever escapes fastest wins £500 for the charity of their choice. That's a fantastic cause, and every good competition needs a trophy.

Their rooms are properly built: loads of props, loads of electronics, everything feels real. A plastic cup off the internet wasn't going to cut it. I wanted something that looked like it belonged in one of their games, and I told myself I had loads of free time. (Spoiler: I did not.)

The reactor core

The idea was a little sci-fi reactor core: a solid plinth with a plaque, two chunky pillars, curved reactor arms, and a big orb sitting in the middle. The orb would be printed in translucent filament so I could stuff LEDs inside, add a button, and make the core glow. I even toyed with a sound module.

I put it together in CAD, with a bit of inspiration from ChatGPT, and previewed it in my own STEP viewer for macOS, which you can grab from this site.

Printing the prototype

Into Bambu Studio it went. I spread the parts across my printers, and through the magic of time (everyone's seen a 3D printer print) I had a grey PLA prototype on the desk. It was kinda cool. The print quality was genuinely good, with just a bit of stringy spaghetti where the printer had struggled on a few overhangs.

And that's when it hit me: a grey plastic trophy isn't really a trophy. It needed painting. I'd never painted a print before.

Sanding. So much sanding.

I'd done my research: sand it, prime it, paint it. Easy. The sanding is mostly about giving the paint a key to grip onto rather than smoothing anything, because a good print is already pretty smooth.

I started on 60 grit, moved up to 240, and eventually took everything down to around 800. On a model this fiddly, with pillars full of grooves and arms with awkward curves, it takes forever. About ten minutes in I was already regretting it, and wondering whether I should have just printed the whole thing in colour. Probably wouldn't get quite the same effect, though, would it?

> ⚠️ Budget far more time for prep than you think.
> The sanding took longer than the printing, priming and painting put together.

The worst priming job ever

After a heroic rummage through the shed (bleeped in the video, for good reason) I found the daddy of all airbrushes, a stash of airbrush acrylics and some weathering paints. The plan:

• prime everything
• base coats of black and silver
• mask up the details and airbrush them
• weather it all so the imperfections look like starship battle damage rather than "the 3D printer went a bit wrong"

Priming was done with spray-can enamel, and I'll be honest, it's probably the worst priming job ever. Rattle cans and fiddly geometry don't mix, and I didn't mask properly because "it's just primer". It was a pretty rubbish finish.

> ⛔ Mask everything, even for spray cans.
> Even for primer. Future you will be grateful.

Masking, airbrushing, and a change of plan

Masking all the parts so I could grade the colours was a massive pain. I also used the cheapest masking tape known to humanity, which splits every time you look at it.

Somewhere around here, reality caught up. I'd planned a proper wooden plinth, but I just didn't have the time, so the base got 3D printed too. It's not quite as nice as wood, but it looks right, and it has a recess for a brass plaque.

Then came the moment of truth: peeling off the tape. It was looking pretty cool. With the black and silver on the pillars and the orb sat on top, I genuinely laughed. Look how cool is that?

The big surprise of the whole project was the airbrush. It gave a far better finish than the rattle cans. That's almost certainly down to my inexperience with spray cans, but if you're starting out, I'd go straight to the airbrush.

That's a pickle

Assembly should have been the easy bit. Woodwork I can do, electronics I can do. This stuff? Not so much.

I'd designed it to screw together, then couldn't remember how half of it was actually meant to attach. My fix was 3D-printed dowels: knock them into the pillars, the base and the top plate. Some went in "right nice". Some went in a bit bent. Some needed a hammer. It's gonna work.

Gold leaf and weathering

To finish it off, I put gold leaf on all the bolt heads. That's an excellent way to end up with gold leaf on every surface you own, including yourself. Then came a final pass of airbrushed weathering to dirty everything up and tie it together.

Somewhere in the middle of all that, I realised I'd started this project by saying I'd make a trophy and was now using an airbrush, a laser and gold leaf. That's how scope creep looks.

So, did it work?

Mostly, yes. Stood on the bench next to the grey prototype, the difference is night and day: silver and black pillars, weathered reactor arms, gold bolt heads, and that big red core. I was really pleased with how it turned out.

Surely something wasn't all gravy

Oh, plenty.

• The plaque: I planned to laser engrave it with my AtomStack. That didn't work at all, so the trophy went out with a blank plaque.
• The electronics: no LEDs, no button, no glowing core. I completely ran out of time. (They may add the LEDs themselves, which would be brilliant.)
• The handover: I delivered it, and my camera failed, so there's no footage of the big moment. Typical.

Fundamentally, I don't think I did it justice. I handed it over before it was really finished properly, and I put way too much pressure on myself to get it done.

Final tally?

My first painted print, and four things I'll take into the next one:

1. Prep takes forever. Sanding is everything, and it takes way longer than you think.
2. Mask everything. Even if you're "just" using spray cans.
3. Airbrush beats rattle can. By a mile, at least in my hands.
4. Give yourself time. Projects like this are meant to be fun, a bit exciting, and a chance to learn something. Don't take one on when you've got 200 other things going on, or you'll rush it and do half a job.

Good luck to every business taking part. I hope the event raises loads for charity, and I hope you escape.

What's in it

• Printers: Bambu Lab, sliced in Bambu Studio
• Filament: PLA in grey (prototype), brown (base) and red (the reactor core)
• Fixings: 3D-printed dowels (and a hammer)
• Sandpaper: 60 → 240 → 800 grit, plus sanding sponges for the curves
• Primer: spray enamel
• Paint: airbrush and compressor, acrylic airbrush paints (black and silver) and weathering paints
• Masking tape: the cheap stuff splits, so learn from me
• Gold leaf: for the bolt heads
• Plaque: brass, blank (the laser engraver lost this round)
• Design: CAD, previewed in my STEP viewer for macOS