If you want to make sure of the high quality of color separation for screen printing provided by the Magic Buttons plugin, then on this page you can download examples of color separation files in high resolution.
These files are complete Photoshop Channel Separations.
The archive contains files of several types of PSD, EPS, as well as a JPEG file for preview. You will need a RIP to rasterize these files. But if you do not have a RIP, then you can use the finished rasterized version, it already has registration marks, signed colors in accordance with PANTONE. You just have to print the file and make the meshes.
In case you haven’t come across working with such files before, then you can try your hand. These files are completely silkscreen ready.
Make sure printing such impressive images is easier than it sounds.