Duplo Train Compatible Action Bricks for Locomotive

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The models listed are custom made in order to be compatible and NOT an official product by LEGO® in any way. 

Action bricks that can be used with certain locomotives. (Requires a color sensor on the bottom of the locomotive)

They need the right length and color in order for them to work. Getting the color right is a little tricky. While the sensor is forgiving to some degree, I only managed to find a few working colors as of yet. 

In case you do not have any color matching / working filament on hand, there are two workarounds:

1. Hit a stationery shop and try finding color matching paper / thin cardboard. 3D-Print the blank version and simply glue the matching color cardboard on top of it.
2. Try recreating the color on your computer and printing them out. This can be tricky though, since you need somewhat color calibrated gear in order for this to work. (or some trial and error…). The printed out pieces can now glued on top of the “neutral” bricks.

A list of color codes can be found here

Known compatible colors / filament

(will keep list updated, please leave a comment if you have found a working color!)

Disclaimer: Color of filament may differ depending on your batch, there is no guarantee those will work 100%!

White | Headlights

• Polymaker PolyTerra PLA Cotton White

Red | Stop

• 3DJake ecoPLA - Red

Blue | Refuel

• Polymaker PolyTerra PLA Sapphire Blue

Green | Reverse

• Extrudr PLA NX2 emerald green
  (kinda works, not reliable though. Some sanding helped but still not 100%)
• Gembird PLA Fluorescent Green (Thanks Repoholoy!)

Yellow | Honk

• No known compatible filament yet  :(

Printing

Blank blocks:

Can be printed with the top facing the built plate

Blocks with symbols:

On my MK3S, the bridging worked quite well and I was able to print them without any supports. YMMV though, I suppose that at least supporting the middle section may be neccesary on some printers. A little bit of sagging is not a big deal though, the blocks work just fine and the little ones really don't care about your sh*tty overhangs ;)

Remember to add the color change for the symbols!