[Geof]

I grabbed one of your pictures and made a minor addition that may not even be necessary.

The sequence I would use is to do the bottom first with the speaker mounting recess, the interior, the four tapped holes and my addition the dowel pin hole. In addition to the dowel hole it will be necessary to keep a tight tolerance on the speaker recess because these are used in positioning for subsequent operations.

Ideally the next operation would be to use a 4th axis, or an indexer, with the part mounted from the bottom; then everything could be finished in one fixturing. With a bit of luck that is; it would be necessary to do the top by coming in from the four sides.

If you do not have a 4th or indexer then you simulate it by making a fixture with a spigot that fits the speaker recess, a dowel pin for the dowel hole and holes for the screws. You are the indexer and simply remount the part for each side. The reason for keeping a tight tolerance on the recess and for adding the dowel pin is just to maintain precision in repositioning the part on the fixture. With a 4th axis where the part is attached only once it is not necessary to worry aboutmaking provision for precise re-alignment. Which is why I say at the top that the dowel hole may not be necessary.

This part is not really a challenge for fixturing but certainly the programming is not trivial.

Having a free form shape which is what it appears you have, means that probably a longish machining time will be necessary to get a good surface finish. this is not important if you are only machining prototypes and pre-production proof of concept units. If you are planning on going into volume production by machining out of solid this could be a killer.

Laboriously machining complex curves into a mold for injection molding parts is fine because it is done once and then hundreds of thousands of parts come out of the mold. But you need to have a demand for enough volume to justify the mold cost. If your expected volumes are too low for molding or you want to maintain a fully machine appearance, which can definitely enhance a product, then you need to look at ways to ehance the efficiency of machining. One way to do this is look at you shape and see if it can be generated by a turning operation on a lathe followed by milling operations. Generating spheres or oblate/prolate spheriods on a lathe is quick and you can get a very good surface finish. Then machining what are essentially facets on these in a mill is equally fast and it is possible to get very good finishes. Following up with a satinizing bead blast process before anodizing could make your part look very classy as well as being acceptably quick to make.