Sorry but got to the party a little late. I have answers to all the clues and almost finished the puzzle. However I have no idea what (1) entails. When my Grammar School changed from woodwork to technical drawing I struggled.
I think I have the five specifications thus identifying the five pairs of columns but I cannot work out what comes next. I think I have the five pairs with touching letters of 4, 5, 2, and 6 but with the final pair (in columns 14 & 15) only having one touching letter. This doesn't seem right and I do not understand how many bars to insert in each column or where.
Any help, guidance, or nudge would be greatly appreciated.
I support other comments about the brilliance of the theme (if only I could finish it!).