For this project, I built an audio interface for a tape recorder used in filmmaking. I had previously designed a version using an off-the-shelf plastic enclosure, but for this one, I redesigned everything from scratch to create a higher-quality aluminum version.  
Everything—from the aluminum enclosure, single- and double-sided PCBs, resin parts, to the custom foam insert for the case—was made entirely using the Carvera Air.

# Aluminum Enclosure

The enclosure started as a 30mm-thick aluminum block, which I cut in half by hand with a saw to create the top and bottom stock for machining. I experimented with various stock-holding methods—including a vise, L-brackets, and MDF jigs with double-sided tape—to machine all seven sides.  
After detailed simulation in Fusion CAM, I ended up using 18 different tools. While it’s possible to reduce the tool count by compromising on finish quality, tool life, or machining time, I chose to prioritize precision. Fortunately, the Carvera Air’s quick-change collet lever made tool swaps fast and easy.

The finished enclosure shows visible toolpaths but feels silky smooth to the touch, with no roughness whatsoever.

# Barrel Polishing

The machined aluminum had a natural shine and clear tool marks, so I used a newly introduced barrel polishing machine to remove them. I polished the parts three times, using barrel media of different sizes.  
This gave the enclosure a smooth, semi-gloss finish with a subtle brushed texture that perfectly complements the tape recorder’s aesthetic.

# PCB Fabrication

Because of the compact enclosure design, using a universal perfboard wasn’t feasible. To fit all the components, I had to design a custom-shaped PCB from scratch.  
Thanks to the precision of the Carvera Air, I was able to iterate the board shape and circuit patterns multiple times within a single day, quickly arriving at a final design.

For the UV solder mask, I found the included roller difficult to use evenly with my skill level. Instead, I adopted a pressing method using a 0.15mm polystyrene sheet and a glass plate—similar to how thermal paste is applied to CPUs. I also tried using silk screen mesh, but this pressing method gave the most uniform finish.  
After UV curing, the board had a glossy appearance, almost like a professionally manufactured PCB. While this process isn’t suitable for mass production, it proves that the Carvera Air is more than capable for one-off builds.

# Custom Foam Insert

Cutting the soft EPE foam insert was by far the most challenging part. It was actually harder than machining aluminum—any chip that got caught around the bit would tear the material, requiring a full redo.  
While minor imperfections might be acceptable for some projects, I aimed for a flawless result.

Through trial and error, I found two key tips: always use conventional (up-cut) toolpaths, and constantly vacuum chips with a powerful vacuum. When chips weren’t fully cleared, I paused the job and removed them manually to prevent any interference with the toolpath.

I was so focused during this step that I forgot to take any process photos or videos—but I’m happy I was able to finish it successfully.

# Final Thoughts

This entire build took about six days, and I’m very satisfied with the outcome. Since getting the Carvera Air, I’ve been able to take projects from prototype to final product entirely on my own—and that’s made the process incredibly enjoyable.  
I’m looking forward to applying this know-how to future projects, including MIDI controllers, synthesizers, and audio effects units.

[MakeraContest] Audio Interface for Tape Recorder