Source Card Images
The card images are what is actually going to be printed, so getting print quality card images is essential.
According to u/Chilli_Axe the highest DPI that MPC can print is 800DPI, this means that the highest quality MPC can print is 800 pixels per Inch. The card size we are printing on is 2.48" x 3.45" so the card size should be at least (2.48 * 800) = 1984 pixels wide and (3.45 * 800) = 2760 pixels high.
If the image isn't at least 1984 x 2760 then you won't be printing at the best quality. This may or may not be a deal breaker but definitely something to keep in mind. Check out this discussion if you want to read more about image sizing.
The lower the DPI the worse it is going to look. Do note that it is NOT recommended to use anything lower than 497DPI (1232 x 1714). Even 300DPI (744px x 1038px) looks bad and text will come out blurry. Anything 300DPI or below MPC will alert you to the bad quality.
For this reason we will only obtain our images from sources that are at least 500DPI, luckily there are a few options.
The easiest way to obtain the images you are after is to use http://proxycommander.com/. You can copy and paste an entire sheets worth of card names from the excel sheet and into proxycommander, make sure you click the "Allow lower resolution files".
Start with the Artifacts sheet. Once submitted, select the 'variant' of each card you want, click download and wait.
Once you've finished each Excel sheet take all the images out of your download folder and put them in a new folder structure. Create a folder for each card type, for example:
Move all the artifact images into their respective folder. Continue this process until you have all of the images of the cards you require.
Lastly obtain a card back.