I'm planning on building an ultra-wide pinhole camera. Any suggestions on where to buy these tiny vials? My local camera store has the circular "bulls-eye", and also 2 axis levels (attaches to hot shoe). I'm just looking for the single axis vial to imbed into my wooden camera top. I live in the USA, so a legit mail order source in the 50 States would be great.

I've seen MarkB's post on adding a level which is serving as my inspiration, but I haven't been able to find locally a similar cheapy level to tear apart to use in this project.

thank you!