I have to fess up and say that my tools are extremely limited
I have an old table saw that I had to fix first as the blade was not perpendicular to the table so I had to remedy that so I could get square cuts.
I had that and a jig saw and I used a Dremel drill screw holes. All the radius forming (edges, corners) was done by hand with a sanding block.
This was also the very first time I'd done tolex. It was very much a figure it out as I go kind of project. Id love to tell you all i had some grand plan but that's not the case.
The joints are very primitive. Just glued and screwed with a 3/4" strengthening joist. The cab is extremely strong. It's not the fanciest method but it's effective. I countersunk the screws just enough so I could put a veneer or plastic wood and sand smooth.
The Tolex is Wine Taurus and the grill is Oxblood colour. I think it looks a little funny in the pic. I used 1/2" baltic birch ply for the cab. The bottom is 3/4" as I had that piece laying around.