DX and common print ratios

Someone posted (somewhere here) about cropping and visually cropping in a viewfinder. Their objective was to shoot so the image would print on a certain size of paper.

I recall a device with two sliding pieces of cardboard that showed you the crop area of an image. I thought this might be a useful graphic.

This is a close approximation of various aspect ratios set over the DX aspect ratio It has nothing to do with resolution.

I hope it is helpful