If you make a Joy Fold card
Joy Fold Card Tutorials at Splitcoaststampers, the remaining piece of base cardstock is a great size for a slimline card. I made a Joy Fold card yesterday. I scored the remaining piece of cardstock down the middle, and I now have a card base that measures 3 3/8 x 8 1/2 inches when folded. I make my own sizes, so that little 1/8 inch off the "standard" slimline size doesn't bother me at all. I might even cut it down a little to fit into some of my thin envelopes.
One thing to note about the measurements for the Joy Fold card patterned paper pieces:
The two 2 3/4 x 4 inch pieces of patterned paper should be 2 3/4 x 3 3/4 if you want an even border.
I had forgotten how much fun the Joy Fold cards are to make, and now I can get a 2-for-1. Happy card making!