With issue 4628 hitting your doormats now I would just like to forewarn anyone wanting to rush out and start making this that there are errors on the baseplate Drawing Fig 4, a revision will be posted in a later mag as I pointed it out to Martin over a week ago.
Also treat Figs1-3 as very general sort of arrangements as parts are not drawn to scale and dimensions are wrong.
If anyone really wants to get started on this over Xmas then PM me for a revised sketch.