All done by 8 this morning, so nothing like as scary as it looked at first.
A very clever and original construction - not one that I've come across before - though not un-akin to the 3D calendar puzzles; the scytale should become a regular crossword format ( if it isn't already, missed by me).
I may have an advantage in having spent much of my professional life surveying, designing, making and installing metal balustrades for helical staircases, so the 3D visualisation of this particular geometry is second nature to me - a little thought at the start, and a common-sense assessment based on the numbering layout, gave me the repeat number and the approximate diameter of the helix very early on, and from there it was just a matter of worrying-out the rather clever clueing; cutting, pasting and wrapping weren't necessary.
The nature of the undefined thematic items also PD'd early, followed quickly by the identity of the 'work', wittily indicated in the preamble- although the timely four-word message only dawned on me towards the end - I'd had the wrong cliché-d coda in mind.
Very enjoyable on several levels - thank you, Kea - and a Happy New Year to all.