26th and 27th have the hardware Dan posted.

Edited June 28, 20231 yr by 26th-Z

Here is a pic of a couple I saved from a 12/70 parts car. The measurements agree with those posted by @AZ-240z back in 2016, post #6. I was able to determine the flat head screw is a M3.5 x 0.6mm pitch x 20mm long.

On 6/28/2023 at 6:57 AM, Grapes said:

I couldn’t find any of the male snaps either so I made my own from bits and pieces from the Home Depot hardware drawers.  Took the 3 pieces shown and stacked them together then glued with epoxy.  I also cut out some wood backing washers like the originals.  Notice that Datsun put a small piece of tape held the nut onto the backing washer so it didn’t fall off during assembly.

That looks a lot better. I am going to copy your idea, thanks for posting that!

Does anybody have outer diameter of the snap at the widest point?
Masonite is "1 5/8" in dia. and 3/16" thick" from an earlier post in this thread.

Here is a quick sketch of the OE snap. It's 10.2mm [.40"] diameter at the top.

Edited July 4, 20231 yr by CanTechZ

Just wanted to thank everyone who contributed to this thread. I finished up my firewall snaps and carpet snaps, and am satisfied with the results. Not perfect, but those snaps weren't on my firewall when I got the car, and they seem to be unobtanium. I guess I could make a 3D printed model, and maybe get some online place to print it in metal. might work. 

They look great, plus no one will even notice….just you! 😆