I am in agreement with the other posters. New fabric would look new, but I do like the idea of a dark border, I would go with charcoal, navy or dk brown. That would frame it nicely. I also wondering why you want it bigger. a 4 to 6 inch border would give you a nice size quilt.

I'd probably add a narrow navy blue border to contain the craziness and then a green or blue gingham for the final border.

I'd go for a gray, brown or muted blue border if you want to add size. That said, to me that is the size I like to make for couch/cuddle quilts. I wouldn't add any blocks at all.

I would do a small 2" "stop" border of Ivory or Cream on the inside, then a large 6"-8" solid color border on the outside. The solid borders should "frame" the scrappy quilt nicely without being distracting. I think a chocolate brown outer border would look nice - to match the chocolate triangles in the quilt.

I'd probably add a muslin border (or a nice, soft cream) since it is more in keeping with the era of many of the fabrics.

It's gorgeous! I would loved to have found it....

How are the seams? You could disassemble and use a sashing around every block, or 4 blocks together to make one block, if there are enough blocks.

or at least a muslin border. it doesn't need more blocks, just finishing. have fun and good luck.

If it were mine, I wouldn't add to it. I might secure it with a pale border or one to color match with the darker triangles, and a backing fitting for the fabrics. Perhaps I'd quilt around the squares, and then fold it up and add to a bookcase or piece of furniture rarely used. That's my opinion of what I would do.

If you really want to extend it I would suggest a narrow dark border or narrow muslin, followed by a slightly narrower red polka dot border and then a final wider border to match the first narrow border.