The housing is composed of two pieces that snapfit together. The bottom is simply a hollow hemisphere with a ring around the top that snaps into the cover.
The cover is where everything mounts. On the inside you can see the mountings for the PIR and HalloWing as well as the cutouts for the sensor dome and screen. The place for the speaker (which is self-adhesive) and the speaker grill are also visible.
On the outside face you can, again, see the cutouts for the PIR dome and HalloWing screen as well as the speaker grill. Additionally, there are the insets for the touch pads and NeoPixel ring.
Print with supports from the print bed. The bowl should be printed open side down, while the face should be printed with the outside down. Once printed, remove the supports and clean up. Test fit the touch pads, NeoPixel ring, and speaker, tweaking as needed to have them fit well.
The USB breakout cutout requires some special attention. It is so narrow that supports were eschewed in favor of some post-print cleanup. carefully trim material out of the side wings until the breakout slides in... just; it should be held in place with friction.
Not to worry! You can use a 3D printing service such as 3DHubs or MakeXYZ to have a local 3D printer operator 3D print and ship you parts to you. This is a great way to get your parts 3D printed by local makers. You could also try checking out your local Library or search for a Maker Space.
You can download the STL files using these links.
Here are closeups of the snap-fit joints on the face and bowl.
Making circular snap-fit joints in Fusion 360 is covered by Noe Ruiz in this video tutorial.
Now you can mount things to the face. Start with the touch pads. Drill a small hole in each depression at the speaker end, since that's closest to the touch pads on the HalloWing. One will be near the USB breakout so be sure you stay clear of it.
Slip a piece of silicon covered wire through each hole. It's far easier if you strip and tin the ends first. Solder these to the back side of the touch pads you made earlier. Secure them into the depressions with a little hot glue, pulling the wires through as you do so.
Next is the NeoPixel ring. Hold the ring in place and mark hole locations for power, ground, and data-in. This can be done with a drill bit that will fit through the ring PCB holes, or a very fine tip marker. Remove the ring and drill the holes. Make them large enough to accept a wire from the JST connector you've prepared for the NeoPixel ring.
Thread the wires though the appropriate holes and slip the tinned ends through the ring PCB from the back. Carefully solder in place.
Put some hot glue in the ring depression and carefully seat the ring in place, while taking up the slack in the wires.
Press the USB breakout into the cutout in the side of the face. It should barely slide in, and be held in place simply by the pressure and friction from the plastic. Slide it in until the connector protrudes just slightly.
If it's loose, a couple dabs of hot glue will hold it in place.
Next up is the HalloWing. Mount it using four of the short M3 bolts.
The PIR is then mounted with the small M2.5 screws.
Next, peel the tape off the back of the speaker to reveal the adhesive. Press the speaker into place, with the leads on the same side as the HalloWing's speaker connection.
Finally connect everything to the HalloWing. The touch pads require a dab of solder to connect to the outside touch pads. Everything else plugs into the matching connections.
Connect a battery and line up the snapfit parts of the bowl and face. Taking care that all wires are are tucked inside, carefully snap the pieces together.
You might find that the bowl needs some weight in the bottom. If so, some plastic covered ball bearings stuck into the bottom with hot glue should do the trick.