Certainly not too sophisticated. Excellent condition, printed on somewhat heavy stock. May be from the 1930s. Postcard back photograph of 5 men standing on and around a railroad steam-driven engine . Standard postcard size.
Photo is a bit worn and soiled, and has a nick through it near lower right corner.
But not square. Glued into a small oval-shaped holder. Fairly nice condition, but there is a surface disturbance in part of the coating on the tintype. I do not know anything about the process, so I do not know what it is, but it is at the edge of the image only. Larger image of detail.