With the back basically finished (a little external clean-up to do), it's time to glue the ribs to the back. First step is to loosen up the blocks from the form. A few taps with the hammer break the weak glue joint. Then, split out the excess portions of the blocks to give some 'wiggle-room'.
With just a little flexing, the rib assembly slides out.
Now, I can clean up the linings, which I roughly shaped with a knife prior to removal from the form, and trim the blocks down to their final shape. With that done, a little fresh hide-glue and a quick clamping.
Starting to see a box here! Now to finish the top and get it glued into place.