All of the parts are designed to be 3D printed using various colored PLA filament. The majority of the parts are "friction fitted" and snap fit and lock together.
The top cover (the one with the facial features) is dual extruded in black and white filament. The STL files joy-top-black.stl and joy-top-white.stl are the top half of the case that are combined together to form one piece. 3D printers with a toolhead capable of dual extrusion have dedicated slicing software. The Ultimaker 3 features CURA slicer which requires setup for preparing models for dual extrusion. See Ultimaker's Getting started with Printing with Two Colors in CURA.
The STL file joy-top-face.stl is the top half of the case that is designed specifically for single extrusion 3D printers. This could be printed in different colors using the "color swap" technique where the printjob is paused, the filament is changed, and then the print is resumed – Repeated a few times can result in a 2-color 3D print. See our Boomy The Boombox guide for details on how to accomplish this using SImplify3D.
Main two piece case snap fits together. The left and right pads are friction fitted into the top half of the case. Various details are a combination of securing with adhesives and 3D printed via dual extrusion. Most of the electronic components are secured to the top and bottom half of the case with machine screws.
CURA Slice Settings
Here's a screenshot of the settings used to 3D print the top and bottom halves of the case. To get the most accurate tolerances for the snap fit features, you'll want to adjust your slice settings accordingly. The parts were tested with PLA filament, other materials that have more shrinkage such as ABS or Nylon may have different tolerances.
The left pad (the one that houses the 4-action-buttons) required support material to 3D print properly. Support material helps 3D printers resolve overhangs and undercuts that would not be possible otherwise. 3D printing slicer software such as CURA and Simplify3D features tools and settings for setup support material. I used a pair of precision flat pliers to remove the supports by pinching and pulling it off the part.
The pink strips in the bottom case piece are printed separately and can be attached with either double-sided tape or adhesives. I used tape called nitto paper tape that is has a strong hold (I actually use this stuff for securing material to my CNC milling machine). Using scissors, cut very thin strips of tape and stick them to the pink strips. I placed the strips with the help of tweezers to ensure they were evenly spaced out.
The right pad features "masking" details that fit over the button actuators. These button masks are pressed into the right pad's cavities and have a friction fit – or can be secured with adhesives. Optionally can be dual extruded, but requires more consideration with support material. The button actuators were printed in several different colored filament. The buttons can optionally be spray painted.