I have two tartan waistcoats, neither professionally made. One I had made by a friend and volunteer at the museum. I had enough cloth to do both the front and the back in tartan, which is a great option if you ever wear the waistcoat without a jacket. I don't have a picture handy of the back, but the tartan is straight on the back, on the bias on the front.


My wife made my second one. This one has a plain back.


Making a bias cut waistcoat uses up more fabric than you'd think, because you have to have enough room to "play with" to get the pattern to line up just right. If I recall right my wife needed a full yard double width to get the two panels for the front of the vest.

If you have enough fabric I'd recommend getting a waistcoat with tartan front and back. The tartan back on my first one never fails to draw compliments.

I, personally, wouldn't want a fly plaid. But it does sound like you have enough material to make a larger plaid as I describe in my blog post, should you decide to forgoe the waistcoat:
http://kiltmaker.blogspot.com/2008/0...ats-plaid.html