It depends on what kind of sights you are using, and what you are trying to accomplish. Look up "Targets" on Google and check out what is there for free to download.
Bead front sights seem to work the best using ROUND bullseye targets. You stack the bull on top of the bead( a "6 o'clock" hold). Pistol shooters long ago learned to leave daylight between the top of their front sights( Usually wide square posts, in comparison to the size of the bullseye)and let their "Eye" maintain the same distance between the bottom of the bull and the top of the sight. It can work with iron sights on rifles, whether BEAD or post.
Chunk Gun Shooters use "sighters". These targets usually have blocks of off-colored squares, that bracket the front sight- side and top, while the top of the rear sight is level with the top of the front sight. This allows for some incredible precision shooting with iron sights at the 60 yd. targets. The Goal of this kind of match is to place the ball as close to the center of an X on a separate piece of paper- which you are allowed to move to where you think your ball is going to strike based on wind and weather conditions at the time the shot is taken. You can look up the Sgt. York Memorial Chunk Gun match site,and I believe they list the scores from last year's match. he winner put 10 shots in a combined string of 3.6-something inches, if I recall correctly.The man who placed Tenth in that match had won the World Champion Chunk Gun match the year before, with a string that was worse than the string he shot that won 10th place in 2010.
You should be able to find a variety of targets, many with 1" blocks, or squares, and 4 inch squares bracketing a white bullseye, that seem to work quite well with Iron Sights.
You can also contact the NMLRA, and they have a whole catalog of targets that are "official" for use in NMLRA sanctioned shooting matches. Very few of these are designed to be used ONLY with scope sights.
If you have access to a photocopy machine, you can make as many targets as you want- either of your own design, or from those you can down load and print off the internet. If you are doing high volume copies, always check with a local print shop to see if they can't make you a lot of copies for a lot less than you will be charged at the dry photocopy machine shops. :thumbsup: