Is it an A37mm you're looking for? With the lens's outside diameter measuring roughly 37mm? Or is it an S37mm that you want to adapt for slip-on filters?
Not sure if that question makes sense. Me no good with words.
For what it's worth, I have 37mm (S37) filters, which measure just over 39mm for slip on. A 35.5mm (S35.5) may have the right dimensions for you, and they are readily available.
Camera-filters.com is also a good resource. They have some obscure sizes.
Also, SK Grimes can manufacture whatever you need if you send them measurements. I haven't used them yet but they have an excellent reputation.