This is called the "Frankenstein Amplifier" because I had a couple of amp cabinets with speakers and no working amplifiers, plus some other bits and pieces that were just waiting to be reduced and combined.
I wired a Crate GX15 into 3 separate speakers instead of 1, and turned a pair of old computer speakers into an overdriven 2nd channel.
Step 1: Gluing and Compressing the Plywood Speaker Panel
I had plenty of 3 ply wood lying around, but this wasn't quite up to the task of handling 5 speakers with heavy magnets in them.
So I cut identically sized pieces, spread a thin layer of wood glue between them, and (as you can see in the pic) clamped the hell out of them! Once dry and trimmed to size, the profile was seamless.
Step 2: Components Used for the Build
1. Creative SBS20 Computer Speakers and amp
2. Crate GX15 amplifier and speaker
3. Speaker from a Champion 600 amp
4. Other 4" speaker
The holes that were cut for the cabinets the speakers original were housed in served as great templates to stencil and cut the new holes.
Holes were cut with an electric drill and jigsaw.
These are the controls from the computer speakers being mocked up for housing fabrication - I used an angle grinder to cut the basic shape out of the Fender Champion housing, then used cobalt drill bits to make the holes for the potentiometers.
Lucky the potentiometers were threaded, so I was able to firmly attach the whole circuit board to the housing.
Here the housing is trimmed to size - I used the pre-existing holes to screw the housing in vertically to the cabinet, but needed a horizontal fastening point to make it a bit more stable.
I don't have any metal bending equipment, so I put the faceplate in my bench vise, then attached my vise grips to the tab hanging out, and bent it 90 degrees - it wasn't a bad way to do it...