dlockh4258 PM'd me and brought up an intersting question for those considering making one of these attachments. Should I make it the width of my mower? Shorter? Longer?
I originally considered telling him to make it shorter than 72" because of the lap you take with each pass of the mower. When I look at my "stripes" in the lawn, they are less in width than the 60" attachment (and mower) I made because on the next pass I cut, the attachment laps over the area I just cut. I was going to suggest he look at what his normal "lap" was, and cut that off each end of the attachment, or just make it that much shorter. I was going to cut mine off, and I believe I lap about 4"-6" each cut... minimum, so that is what I was going to take off each end. I'm glad I didn't.
I took a piece of paper and made a model to see what would happen if I made the striper shorter. It turns out it will leave "unstriped" strips between the striped rows, or stripes of grass that are not layed over (which makes the stripe), which in turn will make the stripes look ragged and not crisp and clean. Make your striping attachments the width of your mower decks. So what if the stipes you leave behind are less in width than your mower... at least they will be uniform and crisp-edged. By the way, making it longer will make the striped rows narrower yet because of excessive lap.