My right shoulder button on my new 3ds is gone! Where can I find a replacement part that isnt for the xl version

I recently bought a very used new 3ds black mario edition. The spring and entire shoulder button was completely missing. I ordered a spring from China so that will be here in a couple months. I have opened it up and am pretty sure I can fix it, I just cannot find a actual button part anywhere that isn’t for the xl size. Please help I’m here because I cannot find this type of part anywhere!