Oh, so they had a matrix carver? I presumed they did it the easy way. O_o Press one side at a time against a soft material (not sure what was used) to create a negative mold, which hardens when it cooled down. Will only be good for a couple of castings and even then fidelity is audibly affected.Roentgenizdat are a little different: each one was carved in the same way as making a phonograph master.
In that end, providing the printer an autoCAD for the dieline might sweeten the deal compared to just providing a packed pdf/indesign/illustrator file (even if it's done by the numbers). I'm not really sure, but it can't hurt to ask. Or, they might just prefer to do that sort of work inhouse.The idea behind starting with a standard Avery size is just that the more mass-produced parts you can use, the easier and cheaper production is. ... well, in the US.