This is the end result.
This is how I did it.
I printed out my covers through Shapeways using the new HP Fusion Jet 3D printers.
"HP Nylon Plastic is Nylon 12 (PA12) printed on the new HP Jet Fusion 3D 4200 printer. HP's Multi Jet Fusion technology is a new printing process which uses agents and lamps to selectively fuse models in a powder bed. The multi-agent process fuses each layer together producing parts with a tensile strength in the z-axis which is comparable to the strength in the x-y plane.
This nylon material has excellent mechanical properties, with strength and density exceeding that of parts produced on other powder bed printing technologies. The strength makes it an excellent choice for functional parts, such as drone parts, RC cars, mechanical fixtures, camera mounts and phone cases. The surface is smooth, finished and semi-glossy, also making it a great material for jewelry, home decor, toys and games. HP Nylon Plastic can be thought of as a general use plastic that has a wide range of applications."
"HP Nylon Plastic is printed using HP's Multi Jet Fusion Technology.
HP developed its Multi Jet Fusion technology leveraging its extensive knowledge and expertise from more than 30 years of leadership in the ink jet printing industry. In HP’s Jet Fusion 3D printing solutions, a uniform layer of powder is deposited on the build platform. Then the powder is heated uniformly to just below sintering temperature using heating lamps above the powder. Next, a set of inkjet heads pass across the powder while depositing fusing and detailing agents where parts will be built in a single, continuous pass. The ink deposits a 2D image of each layer or cross-sectional area of the models. Simultaneously, fusing lamps pass across the powder bed as ink is being deposited. The agents and the energy from the fusing lamps cause the powder to selectively fuse together. The agents and the closed loop thermal control system dictate where and how much energy the powder absorbs so it reaches a perfect fusing temperature in the areas where models are being built. The fusing agent controls where powder will be fused together while the detailing agent is applied to modify fusing and create fine detail and smooth surfaces. Next, the build plate moves down, a new layer of powder is deposited and this process is repeated layer by layer until the parts are fully built.
Similar technologies fuse powder together point by point. But with HP’s Multi Jet Fusion technology, each layer of powder is fused together in a single continuous pass whose time is independent of the density of parts on your build.
After printing, the powder is cooled before handling. Then the build chamber is transferred to a post-processing station. Parts are extracted from the powder while using a vacuum system which collects loose powder. The loose powder which is collected is recycled and re-used for future builds. Excess powder on the parts is removed using air and media blasting guns until they are clean."
Link to more information about the HP Nylon Plastic (Fusion Jet).
You can download the .STL from the Robotis Onshape Account or from GitHub.
The old cover design.
Test fitting of the parts on the OP3.