3D Print Your Own Bicycle Safety Light

Hello fellow makers,

In this Instructable I would like to take you through the steps on how to make this awesome 3D printed bicycle safety light.

The light features a dim red glow that is permanently on as soon as it is powered on, the dim red glow turns to bright red when you're brake lever is pressed to warn motorist and fellow cyclists that you are coming to a stop and finally there are two flashing turn signals on either side that can be turned on and off via a toggle switch that can be mounted on your handlebar.

The goal was to create a lamp that is easy to make, requires very little components and the electronics are very basic and easy to solder.

I will also be showing you how you can design you own using Tinkercad.

Join me to learn how to make your own!...

To make this Instructable you will need the following:

• Access to a 3D Printer

Amazon - Ender 3

I used ASA filament for its weather resistance.

Amazon - Black ASA filament

• 4x Red 5mm LEDs

Amazon - LEDs with resistors (CONSTANT AND BLINKING AVAILABLE)

• 6x Orange or Red Flashing LEDs
• M5 Screw with domed nut
• 2 Part epoxy casting resin

Amazon - 2 Part clear epoxy resin

• White resin pigment/tint or white paint

Amazon - Epoxy resin white tint

• Male and female 4-pin connector

Amazon - 4 Pin connector waterproof

• Some wire
• Hot melt glue
• Resistors

*As an Amazon Associate I receive a small percentage from sales made through provided links at no cost to you, this helps fund future projects.

The main component was designed in Tinkercad using only the most basic shapes.

• I started with a cube and resized it to be 20mm high (this will be the height of the LED housing) and 1.5mm thick (printing with my 0.6mm nozzle this gave me a good 2 layer wall), the length will change as we go.
• Duplicate that cube a few times and move them out of the way.
• Now we can start putting together our LED housing. The first part of the housing is the "arrow" where our turn signal will be, mine is 30mm long along the outside and 10mm wide.
• The top part where your brake light will be is 100mm long (it's easier to make it 50mm and then mirror the whole design in the end for the opposite side) and at a 45degree angle.
• Next we will need to make the middle divider where our LEDs will get mounted through.
• To do this I simply took the 10mmX20mmX1.5mm end and rotated it 90degrees so that it is laying flat, duplicated it and started filling between the walls.
• Group all of your components.
• Next we need the holes for our LEDs.
• Simply take a cylindrical hole, resize it to 5mm (or the size of your LEDs) and arrange it where you want to mount the LEDs.

Now that we finished designing our light we can start printing it.

I printed all the parts in ASA which is trickier than PETG or PLA but because of its higher temperature tolerances and weather resistance it seemed like the perfect filament for the job.

My print settings are:

Material: ASA

Layer height: 0.2mm with a 0.6mm nozzle

Speed: 60mm/s

Temperature: 270 Hotend and 105 Bed

Cooling: 50% with Fan Fang on layers under 30 seconds

In order to diffuse the light from the LEDs better I decided to spray the inside of the light with chrome spray.

To do this I took some masking tape and covered the outside of the light completely to prevent any of the spray getting onto it, the upper edge doesn't matter as much as we will be sanding some of it away later.

I then sprayed a layer of high bright chrome on the inside (white will also work) and left it to dry completely before moving onto the next step.

Now we can start wiring the light.

I started by wiring up the four constantly on red LEDs in parallel paying careful attention to the polarity, leave about 50mm of the ground wire on each end of the string as we want to connect the grounds of all the LEDs together including the blinking ones.

Next I soldered the blinking LEDs in the two "arrows" in parallel, the grounds are connected with the constant on LEDs and then they get a separate wire to the positive terminal on each side via a 47Ohm resistor.

Arrange all of the wires like pictured.

Now we can pour the resin diffuser.

Start by sealing off the back of the LEDs with some hot melt glue.

Next prop the light up so that it is perfectly level, I used an old heatsink to hold it in place.

Now mix up about 30ml of your epoxy resin following the manufacturers directions exactly, put a tiny drop of white tint or paint into the resin and mix thoroughly.

You just want the resin to be cloudy not completely tinted, I accidently put in to much and that dimmed the light output from the LEDs so be careful.

Pour the resin into the cavity until it is completely full being careful not to spill any on the sides.

Leave to cure for at least 24 hours.

With the resin fully cured we can go ahead and finish the lens.

Starting with a coarse 150-180 grit wetted sanding paper placed on a glass pane start sanding the lens of the light in a circular motion until all the high spots are flat.

Whilst sanding check regularly that you are sanding evenly, a good way to get an even finish is to rotate the light 90 degrees every few seconds.

After getting rid of the high spots you can move to a finer 600-800 grit sanding paper and continue until you're left with a matt scratch free lens.

Now you can keep it like this or polish it to get a glossy finish.

Final step for the light is to add your connector and to waterproof it.

As this is all I had on hand I connected some DIP pins to ends of the wires and slipped heatshrink over it.

But if you can I would highly recommend a waterproof connector with clips.

Next I filled up the cavity in the back with some black hot melt glue to keep the internals dry. I recommend getting some of this black hot melt glue as it gives a nice finish to items, it is much stickier and rubbery than normal clear hot melt glue.

The bracket should fit most bicycle seats and would be easy to increase the size if needed.

Align the bracket with the two indents on the back of the light and snap it into place.

As i'm still busy designing the control unit for the light that will fit over the handlebars, I threw together this simple setup to test everything out.

The components used here will remain the same in the final design as I like that it is very minimalistic and should be reliable.

Brake switch:

• 5V power from a USB power supply is connected to the input pin of a microswitch.
• A high ohm resistor is connected between the input pin and the normally closed pin.
• A low ohm resistor is connected between the normally open and normally closed pin.
• Brake light wire connects to the normally closed pin.

With this setup the brake light glows dimly as soon as power is applied and goes bright when the brake lever is pressed.

Turn signal switch:

• Using a single pole triple throw toggle switch connect 5v power from USB to center pin of the switch.
• Connect the two wires from each signal side to the corresponding side of the switch. Remember that the pins of the toggle switch are reversed so if you switch it to the left, the right pin is connected to power.



I designed this simple holder for the controls that mounts onto your handlebars to automatically switch on the brake light as soon as the lever is pressed.

The part in yellow is seperate and can be modified to fit your lever.

I hope you guys find this Instructable useful and if you have any questions please feel free to leave me a message or comment bellow.

Please share your own creations with us by clicking the "I Made It" button below.

Happy making!