This is my version of the Bat Signal from The Dark Knight. I modelled it in Fusion 360, taking inspiration from photos. The model is not to scale and is missing many details. The Bat Signal is functional, with a DC jack for 12V, power switch, fuse and 1W G4 LED bulb.

I have only tested this with 1W bulbs, and using a ceramic bulb holder I have had no thermal issues. You must conduct your own testing to ensure that your chosen bulb/holder combination is suitable and safe!




Required Hardware

• 6 x M3x12mm machine screws
• 10 x M3 washers
• 2 x M3 nuts
• 1 x DC Power Socket
• 1 x Power Switch
• 1 x Ceramic G4 Bulb Holder (mine have mounting holes 20mm apart, and the bulb is 7mm above the mounting holes. I have no idea where I got them- I've had them in a drawer for years)
• 1 x 5x20mm Inline Fuse Holder
• 1 x 5x20mm 200mA Glass Fuse (or appropriate for your bulb wattage)
• Superglue

Build Guidance

• I recommend printing the main body, lens and bezel with a brim. I printed the bezel without a brim initially and I had to reprint it because it warped. The stand doesn't need a brim, I just forgot to disable it (see pic) :-)
• Supports are needed for all parts except the lens.
• Use superglue to stick the bat symbol to the lens. The main body has a keyway to help align the lens. Use a couple of dabs of superglue to fix the lens to the body. The bezel isn't keyed, so must be aligned manually, but this is easy. use a couple of dabs of superglue to fix in place.
• Keep your wiring neat and make sure it doesn't get in the way of the bulb!
• You should be able to tap the holes in the Main Body using the M3 bolts, but this will depend on your printer settings.
• I put a washer between each stand arm and main body side- this was a real pain to get in but allows for smoother tilting.
• a spotlight-type bulb is needed for the bat symbol to be projected correctly. I tried using a 24-LED G4 bulb (left in pic), and the effect was awful.
• A fuse is recommended for safety- omit this at your own risk.