I have done a few things with 3D printed speakers before (Two Way Tube Speaker and 2 Way Orb Speaker) and I came across some nice looking (and at the time dirt cheap) 2 inch full range speakers on eBay. What could I possibly do with a couple of these? Bring on the 3D Printable Modular Sound Bar/Center Speaker! I ordered 10 of the units for around 25 Aussie dollars shipped and began the design - and this is the result.
Each speaker get's its own enclosure that attaches to the next enclosure with 3 small screws. Depending on the type of speaker you get you can use the different fascias - one allowing you to mount the speaker to the front of the fascia or one where the speaker mounts between the fascia and the enclosure. The fascia attaches to the enclosure with 4 smalls screws. I printed my sound bar using red PLA for the enclosures and black for the fascias and sides, which turned out quite a nice combination.
Combine any number of speakers into your own sound bar - I used 10 and hooked them up in series-parallel in order to end up with around 4 ohms impedance. The total width of my sound bar is 72cm (nearly 2.5 feet or 28 inches) which gives it a sleek look. Of course, you can also use 2 or 3 speakers units together, put the speaker on its side and voila, you have yourself your left/right and surround speakers as well!
Depending on what type of connection you want you can just drill a hole in the back of one of the speakers and hook it up straight to your amp (center speakers are usually not stereo). Alternatively you can also build an amp into the sound bar - I used the trusty old KEMO 12 Watt amplifier module, which works a treat treat in this setup.
For the enclosures themselves you should be able to print all parts without the need for any suports. I used .2mm resolution at a speed of 6cm/sec and everything came up nice. If you want to add the amp as well you will need to use supports to print the brackets.
** You will need to have some experience in soldering and electronics to complete this project.