In case you missed this Adafruit video and project from 2015 (I did), in it, the Ruiz brothers show you how they designed, 3D printed, polished, and assembled a gorgeous 3D chess set based on the characters in Adafruit’s Circuit Playground series.

The chess set itself is really lovely, with a fun translation of the Circuit Playground characters into chess pieces (Ladyada as the Queen, Mosfet the cat as the King, Adabot as the Knights, and the LED characters as Pawns). The chess board is 3D printed as a snap-together matrix into which the playing squares press-fit.

But the really impressive thing here is the use of metallic filaments, copperFill and bronzeFill, which have metal particles infused in them. On the Adafruit Learning System tutorial for polishing copper and bronze infused filaments, the Ruiz brothers strongly suggest using an all-metal hot end when printing with these metalized materials:

Produced with a micronized copper powder which has been infused into a common PLA plastic, copperFill will print easily using an all metal hot-end. Colorfabb warns against using any hot-ends which use a teflon isolator coupler, as the filament has been shown to clog these devices.

The other thing that’s special about this project is the use of the jewelry tumbling technique to smooth out and polish the playing pieces. The print polishing tutorial above shows you how to use different sizes of brass screws in your tumbler as the tumbling medium. The brothers explain:

Abrasive material is needed to help bring out the copper metal shine. We used brass screws of different sizes for surface finishing, deburring and polishing. Use wood brass screws sizes #00 to get into the small nooks and crannies of parts, while #2, #4, #6 are used for bigger areas of the model. You’ll want to use a good amount of screws – about 50 to 100 screws should be enough to get a good shine. Water or any other liquid is not required.

What a metal-infused print looks like after being tumble polished with brass screws as the tumbling shot.

You can see the full tutorial for making the chess set, along with all of the .STL files, here. If you haven’t worked with metal-infused filament and print polishing before, you’ll also want to check out this tutorial.