Subway Jet Racing Pod Scale Model

About: I'm an industrial designer and inventor. I make furniture, decorative boxes, and other fun stuff in my free time.

This is a little self-indulgent, but I figured I'd share the process I went through to 3D print and assembly a scale model of the jet racing pod that the protagonist in my novel SHIFTER flies in the subway tunnels beneath an alternate near future New York city. The STL files for 3D printing are available on my GrabCAD page.

*Shameless plug - you can buy a paperback or e-book on Amazon:

In the bleak alternate near future New York of 2025, Ellen, an over-educated, under employed delivery girl gets pulled into the mob controlled underworld of illicit SHIFT racing in the twisted maze of subway tunnels beneath the city. SHIFT technology allows for objects to pass through solid matter. In this future where, economic and environmental decline has worsened and the gap between rich and poor never been wider a single act of defiance against the corrupt protectionist thugs on her street leads down a path to understanding the nature of her city and its true masters. Her experience joyriding in stolen cars as a teenager becomes extremely useful as she enters a racing league where various conflicting underworld factions recreate the bloody Roman Circus Maximus using high-tech miniaturized aircraft in the tunnels of the city. In these tight confines and absurd speeds crashing is just a matter of time, but the mysterious SHIFT technology re-purposed from military stealth aircraft can land you on the right side of the razors edge between life and death.

Supplies:

Ultimaker 2+ FDM 3D printer & white PLA filament

Formlabs Form2 SLA 3D printer & whatever resin is handy

Cricut Maker vinyl cutter with red & black adhesicvinyl

X-acto knife, small needle files, & sandpaper

4" clear plastic DIY Christmas ball ornaments

Thick wire you can bend or big paperclips

Cyanoacrylate glue

Automotive spot filler

White & black spray primer paint

Assorted colors of acrylic paint

Small paintbrushes

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Step 1: Parts to Print & Cut

I originally built this model in SolidWorks back when I was writing the book and super bored at an old job. To make printing and painting easier I broke the model into a bunch of different bodies to print separately instead of needing to get really crafty with tiny paintbrushes. This allows for some 'posing' of the vehicle. The part breakdown is below.

FMD filament printer parts:

  • main body right - side wing, tail fin, front canard, air scoop, main fuselage.
  • main body left - side wing, tail fin, front canard, air scoop, main fuselage glues to other half.
  • elevator right - snaps into the wing.
  • elevator left - snaps into the wing.
  • rudder right - snaps into the tail fin.
  • rudder left - snaps into the tail fin.
  • stairway - has a tab on the back that slots into a corresponding hole in the main body assembly.
  • tank right - has a post that slots into a corresponding hole in the main body.
  • tank left - has a post that slots into a corresponding hole in the main body.

SLA resin printer parts:

  • ball ring right - glues onto the clear dome.
  • ball ring center - glues onto the clear dome across the lower front and its tips slot into notches on the ball rings.
  • ball ring left - glues onto the clear dome.
  • catcher - glues into a pair of anchors on the underside of the main body near the tail.
  • hatch door - fits into the corresponding porthole in the stairway.
  • hatch linkage - fits into anchors on the top of the stairway and hatch door (pins may need to be removed).
  • roll-cage - connects to the top of the stairway with four posts and corresponding holes.
  • front, middle, back vents right - a single part containing all three exhaust vents. Each part has posts that fit in the underside of the main body. Should be positioned so the louvers are aimed down.
  • front, middle, back vents left - a single part containing all three exhaust vents. Each part has posts that fit in the underside of the main body. Should be positioned so the louvers are aimed down.
  • hinge right - connects the catchers mitt linkages and main body via an anchor on the underside near the front.
  • hinge right - connects the catchers mitt linkages and main body via an anchor on the underside near the front.
  • linkage front right - a curved part that holds one half of the catchers mitt.
  • linkage back right - a straight part that holds one half of the catchers mitt.
  • linkage front left - a curved part that holds one half of the catchers mitt.
  • linkage back left - a straight part that holds one half of the catchers mitt.
  • scoop right - one half of the catchers mitt. Has holes to connect with the linkage parts.
  • scoop left - one half of the catchers mitt. Has holes to connect with the linkage parts.
  • ladder bracket right - connects to the main body via a slot at the rear and holds half of the ladder.
  • ladder bracket left - connects to the main body via a slot at the rear and holds half of the ladder.
  • intake door right - Snaps onto a T-bracket at the front of the main body and should be able to rotate to match the profile of the air intake outline.
  • intake door left - Snaps onto a T-bracket at the front of the main body and should be able to rotate to match the profile of the air intake outline.
  • ladder - is held to the main body with the two ladder brackets.
  • pilot 1 - the bottom shell of the pilot and inner cockpit part. Gets glued to the top pilot part.
  • pilot 2 - the top half of the pilot and inner cockpit part. Once mated to the bottom half the end of the rod on the pilots back is glued to the inside of the stairwell.

Step 2: Printing, Filling, Filing, Priming, & Painting

There's a lot of room for customization when it comes to painting this model, but I decided to go with some space-shuttle inspired black and white primary features with a few safety yellow parts sprinkled in too.

The main body gets a good coat of matte white primer and make sure to fill and sand the split between the two halves. A lot of this area is concealed, but across the upper spine it's pretty exposed until you get the ladder rungs installed. I broke the whole batch of parts into lights and darks based on what top-color would go on at the last step. Yellow is easier to paint over white than black. The black parts mostly stayed dark colors with a few highlights of cast-iron or silvery metal for some highlights.

The only parts that really require any skill to paint are the fuel tanks that get silver and black buckles and straps over the main yellow, the hatch door which gets a yellow wheel, and the exhaust vents that get a silver bezel. I decided to paint the front canard wings black to match the rudder and elevator areas for the sake of uniformity.

Step 3: Casting Disaster!

I originally planned on casting a half-inch thick thick, hollow cockpit dome, but did not have much luck. I had 4 inch Christmas balls for molding the outside but for the interior, I needed something that could be broken up and picked out without causing too much damage to the inside of the acrylic dome.

My first attempt was to cover a Styrofoam ball with sculptey, but that was too tacky and didn't smooth out very well. Second try was to coat a foam ball with Mod-Podge glue and then paint it with polyester resin. This may have worked, but was a bit of a pain to get as smooth as I wanted. The one I actually tried casting around was a foam ball covered in candle wax that I painstakingly smoothed out with the back of a hot spoon on a long handle. Once I was happy with the wax ball I stabbed the 3D printed part that would mold the egress hole into the foam and glued on the Christmas ball halves.

Casting was a huge mess as I didn't make the pour hole or the vent hole in my mold big enough. I also had no funnel so I ended up making a kind of pastry bag from a Ziploc bag with a corner snipped off. With this I was able to fill the void between the wax/foam inner ball and clear plastic outer shell. The next morning when I went to check on the casting I was surprised to find that a bunch of the wax had melted off the foam and floated to the top of the mold - destroying the casting.

I did have one last thought to 3D print an inner ball and egress hole in one shot but it would have been too much trouble trying to get its surface glassy smooth. Ultimately I just use the Christmas ball halves as is and oriented the split so it went up and down and didn't make the side view of the pod too ugly.

Step 4: Tiny Pilot

In order to at least try and preserve some feeling of having a thick cockpit dome I made a quick model of what the pilot would look like crammed into this tiny space. At 1:12 scale the heroine of my book would be around 5 inches tall (she's tiny but fierce!) Sitting cross-legged she takes up a lot of space and you can easily imagine how tough it would be to wriggle your way into the cockpit.

The figure is not something I modeled on my own - it's an off the shelf model that people use to illustrate the scale of various products in relation to a human form.

The cushion she's sitting on is a dark burgundy while her suit is jet black. The heads-up displays and control yoke are light gray with phosphorescent green screens, which I also made reflect in her goggles.

Step 5: Final Assembly

The only part of the assembly that isn't very straight-forward is how the catchers mitt goes together on the underside of the pod. In the book, racers use this articulated mechanism to grab extra fuel and other power-up type things. Its intended to swing down and forward while opening up to make a larger scooping area. The screen capture from my CAD model does a better job of showing where things go than I could put into words.

The last step is to apply the vinyl decals on the wings and tail fins. Once that's done it's off to the races!

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    Discussions

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    mydian_nightshade

    17 days ago on Step 5

    I just realized that I didn't have a link to the STL files - that's fixed now :)