Now that the egg-shaped body for the pair of speakers is all built, I can move on to some of the details still missing.

First of all, there is the bass port. In the front baffle of the speaker I have made a flared-out hole with a diameter of 35mm. In order for this to actual function as a bass port, there needs to be a pipe behind the opening which needs to be tuned to a specific, speaker driver dependent, resonance frequency by making it the right length.

Since the inside of this pair of speakers is egg-shaped just like the outside, it’s a bit awkward to fit a straight pipe in it. For that reason I decided it would be best to 3D-print the bass port since I would be able to make it the exact shape required.

Using the fully assembled CAD model of the speaker I made at the beginning of the project, I added a new sketch plane down the middle of the speaker vertically. On that plane, using the Fit Point Spline tool («CREATE»->»Fit Point Spline»), I sketched a path of 250mm length which follows the profile of the inside of the speaker box nicely. Next, I created a new sketch on the inside of the front baffle, projecting the port opening onto it and adding a 2mm offset circle around it. I then sweeped («CREATE»->»Sweep») this ring profile along the previously drawn spline. Lastly, I had to make the decision to split the full 250mm length into two sections and print them independently, because otherwise I would not be able to install the entire pipe through the speaker driver opening in the front baffle of the already fully assembled speaker box.

After printing, I glued the upper section in place on the inside of the front baffle first and then after the glue had set, I attached the lower section to the upper one with more glue. Not quite ideal, but it’ll do the job I think.

Additionally, I wanted to attach the speaker driver to the egg-shaped box with 6 black M4 screws instead of doing it the way I had done it on my previous speaker builds, using spray-painted wood-screws. Since the metric screws would require some nuts from the inside of the speaker, I quickly designed a circular «nut trap» piece.

One thing I really like about Fusion 360 also is how easy the process from idea to reality is using a 3D printer. The 3D model of the bracket was done in about 2 minutes, then I simply right-click on the body and choose «Save as STL». In the pop-up dialog the slicer program Cura is already pre-set and a click on okay launches Cura with the 3D model on the build plate. Usually the slicer settings from the previous print are still valid, so I can immediately save the GCode file for the 3D printer, then upload it to the Raspberry Pi attached to my Creality Ender 5 3D printer over Wifi and start the print right from the browser. A few minutes later the part is ready to be taken out of the printer. That’s what makes rapid prototyping soooo fun!!

I glue the 6 M4 nuts into the pair of 3D printed half-circles with some CA glue and then attach the whole assembly to the inside of the speaker with a bit more glue.

Almost there… home-stretch!

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