Hollow spark plug for 3mm LED

thingiverse

I wanted LED lights to illuminate the spark inside the printable Toyota Engine cylinder head, so I scaled down the spark plug model from mb20music by 40%, split it in two, and made a hole in the middle of it. Next, I soldered 3 mm red LEDs to microphone wires within the spark plugs, sealed them up with glue, and bonded the tops and bottoms together tightly. There are other methods for achieving LED-lit spark plugs on your scale engine if that's what you want. I decided to connect the ignition cable firmly within the spark plug housing, positioning the solder joint inside the plug itself, secured with a shrink tube wrapped around one of the LED wires. The spark plugs turned out slightly oversized, necessitating an enlargement or sanding down of the cylinder head holes to match your required specifications. You can further scale down the design if needed, but for my printer, scaling too far reduced wall thickness, making the print essentially useless. Experimenting showed that printing spark plug parts in ABS worked best when they could be manually shaped after manufacture. To work on spark plugs made from ABS or PLA safely requires some finesse due to their distinct physical properties; while both materials can be manipulated with caution, ABS generally performs better because it withstands temperature changes better than PLA.