Halloween is only a few months away and if you want to 3D print any components for displays or other holiday projects, you better get busy! How about starting with these festive wall light switches which were de rigueur for all self-respecting mad scientists of the Victorian age.


When you need to illuminate the lab (to see what’s on the slab), you need some of these 3D printed knife throws. They replace the regular wall plate and adapt over a conventional wall light switch. Jeff Kerr, the Thingiverse user who created the original thing, printed his in PLA with 0.2mm layers, 3 perimeter shells, and 20% infill.


There are a number of remixes of this print on Thingiverse, some one-switch and some two-switch plates. There’s even a three-paddle switch plate now.


Several commenters have complained about the difficulty of this print. If you’re thinking about building it, check out the remixes (and read the comments) to see what improvements have been made.

Kerr does offer some tips for successful printing, like printing the plate part a little hotter than normal to insure good layer adhesion. And printing a raft if you have adhesion problems with the built-in support ribs (which people have apparently been having trouble with).

If you do print and install some of these knife switches and you don’t find yourself barking out the following command at least once while throwing them, the child in you may be in need of electrical reanimation.

“Igor, throw the switch!”

[With attendant thunder-clap sound effects, a shambling Igor, etc.]

Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy person’s memoir,” called Borg Like Me.

  • Chris Sanner

    any recommendations on how to get hold of one of these if you don’t have personal access to a 3d printer?

    • Sandy Wood

      You can find knife switches at the hardware store in the electrical department. A Google search will turn up all sorts of options: big, small, brass, etc.

      • Chris Sanner

        I meant “is there any way to order a 3d printed item without having a 3d printer”
        an actual knife switch doesn’t usually work as a wall switch…

        • Gareth Branwyn

          Chris, there are a growing number of 3D printing services, the most well-known of these being Also some UPS, Staples, and other retailers now offer 3DP services. And a growing number of public libraries.

        • Sandy Wood

          You could download the files for the switch from this very page, above, and then commission someone to make the switch for you. Have a 3D printer space in your town? Someone there knows how to make it happen. Or look around at Ponoko for ideas. 1st project is free, I see. Ask around; someone at Ponoko must know how/where to get this done.

    • Roland Blais

      I’ve had good luck finding a person locally using

  • Jeff Kerr

    I’ve just added versions of the files that are easier to print – I’ve removed the built-in supports that were giving people trouble. Just turn on your slicer’s supports option instead. The files are at:

    • Gareth Branwyn

      Thanks so much for this, Jeff. And for letting us know.