Being continued....
a first sand and the corners cleaned up.
Took 2 attempts to get the baffle cut, first time tried the dremel with the circle cutter, was a disaster. Second time with the jig saw a bit better, again a bit of a sand will tidy it up.
And after all my judicious measuring and using a guide block I cut, seems its still a bit out on the fit of the back panels, will need to sort that out. planning on cutting a 3rd section that can go in or out so I can try both open and closed back.
A bit more timbermating and sanding to do, and in the meantime will order some Tolex and other bits an pieces to finish it off. Probably a while till I can get hold of a speaker, unless something pops up on ebay cheap.