So, with our wedding coming on Saturday, I finally gave in and made us one. It took me much less time than I anticipated it would (only 3.5 hours with MANY interruptions from M).
The best tip that I can give you for this project is to go pick up some coordinating fat quarter sets. I picked up 3 from Joann's. It was perfect for what I needed! I didn't cut off any of the selvages, I just sewed over them to hide them. This will save you a lot of time!
+15 fat quarters (or 3 sets of 5 coordinating fabric fat quarters)
+1 60"x104" tablecloth (if you want a waterproof blanket, pick a vinyl tablecloth. I used a fabric one)
+Sewing machine, thread, pins, etc
2. Start sewing your across quarters together. When all of your acrosses are sewn together, start sewing your strips together.
3. When all of your pieces are sewn together, lay them on top of your tablecloth (wrong sides together). At this point, I folded the 2 long sides on the quarters a bit so that the tablecloth showed around all edges. I also trimmed about 2-3" off each short end of the tablecloth so that all edges were around the same width.
4. Fold your tablecloth edges in half and then fold them once more so that it overlays your quartered piece. Pin in place. I trimmed down some of the fabric in the corners so that they laid a little flatter and some that it wasn't so thick.
5. When all edges are pinned in place, sew around the edges. I did 2 stitches to make sure everything was held nice and tight. I then made 2 straight stitches down the short side of the blanket so that it would fold in thirds easily.
1. Make triangular pockets in each of the 4 corners so that you can put something heavy in each one to hold it down.
2. Add a pocket with a button so you can put your sunglasses or keys in it.
3. Add ties so that you can roll it and tie it shut.