I draw them in Corel Draw and I think I've got the process down pretty good.
I will share....
After I've designed the banner I group my banner so I don't accidentally move anything.
I move the entire design to the 0x 0y coordinate.
Then I draw a rectangle over the banner. (Generally the square tool will snap to the edges of the design.
I then Pop in a .75" inside contour
Make a circle .25" in diameter and a color opposite of my banner.
Place the .25" circle in the upper right corner (It should snap center on the point of the contour line you just made.
Clone the circle (Defaulted to + on my machine)
Then change the coordinate to a negative number (Example if its 47.25 I make it -47.25)
This puts an identical grommet hole in the exact spot on the other side.
If its a 6' banner I clone it again and put it at the 0 coordinate and that will be dead center
If its an 8' banner, I clone it again and then divide the x coordinate by 3, clone it again and either make the number positive or negative depending on what side I cloned from.
If its a 10' banner I place one in the center like I do on a 6' banner, then I select the the corner grommet and center grommet and copy the X Cordinate. (This should be center between the two grommets) Then clone one of the grommets and paste in my coordinate, clone the one I just moved and then change it to either positive or negative.
I then add a 1" outside contour and break it apart from the original rectangle. This makes my cut line for a taped hem.
Once Complete I delete my original rectangle and send my cut line to the back leaving me my graphic with all its grommet holes printed and a line for my guys to cut with for the hem. What takes me about a minute to do would take my guys about 5 extra minutes to do and god knows how uncenter and off they would pop the grommets.
Kinda lot to read and follow, but I'm actually in the process of making a document with pictures on on how to do it for my other guys to follow because for the life of me, they can't seem to get it right. I had one guy put my grommets in the wrong place and the banner got ripped in a wind storm. Grommet placement is key to quality banners.