I used the plate from my 411G, and the spare 411G bobbin case from another machine. I posted about it here:
http://www.quiltingboard.com/vintage...ml#post6268509
I bet that the flat stock pieces could be made. The guide on the bobbincase, and possibly even the arm on the bottom of the throat plate, but it will take a way better person than me to do it. I think a guide similar to the ones on the newer machine could be made, but the newer guide didn't fit, so I had to kludge. For proof of concept, it's fine
The W&G will be worth restoring. You'll love it. I've seen some, but never gotten my hands on one.
Singer put out 2 different buttonholers that would work with the 401 and other slants, the metal one, and the so called "professional buttonholer" that was a lot more plastic. I've seen a couple of others - Greist, Ruby, Famous, but I don't recall another slant one. I'd be curious to know what brand it was. The manuals do show using the machine for buttonholes, but in practice the buttonholer attachments work way way better.
With the machine alone, my buttonholes always end up more like a weird parallagram than a rectangle.
