Renee,
I bet we could figure this one out easily enough. The bottom is an oval, so put your iron down on a piece of butcher paper (or whatever paper you have) and mark around the whole iron. That gives you a size to start with. Then make an oval around the iron markings adding 2 full inches around, this gives you the seam allowance and the ease you need for the iron caddy to be big enough to hold your iron. Now measure around the outside edge of the oval and add a 5/8" seam allowance to the total. The sides need to be the irons heigth plus the wound up cord on top of it. Use a yard stick to measure it. Then add about four inches (for the zipper and seam allowances). Buy a zipper that will fit all the way around plus some. It will be cut to size after you sew it onto the bottom and a whip stitch hand sewn stop will be put there. You can buy the upholstry zippers by the yard. They have the lighter weight kind for pillows. You will need batting, the iron safe fabric like ironing boards have( The silver iron safe kind), Your fashion fabric, thread to match, embroidery thread (if you plan of decorating the sides like the one shown) and any embellishments you want to use.
You will need 2 fashion fabric ovals, one long side the width we determined to hold the iron, one long side for above the zipper, I would say four inches wide. Then a batting and one set of interfacing all the same as the first set of fabric. And lastly, a set of the fabric of your choice for the lining. The interfacing is ironed to the back of the lining pieces. Trim it to only just cover the seam lines, that leaves your seams easier to work with while making the iron safe.
Now after you cut out that all out, embellish the long sides, make your long strips of your fabric for the ruffles. I would use one and a quarter times the width around to cut them, hem top and bottom with a serger, or a tiny hem. Gather and sew them to the side strips. Stop just past the seam line on either side. You don't need all that bulk inside your seam, then they will lay flat better. Do the same with the top piece. Now remember to leave enough room to sew the zipper on the top of the side piece and the bottom of the top side piece. If you want, sew the zipper on both sides first and then embellish. That will leave you with a flat piece of fabric the zipper in, and the ruffles attached and any embroidery done.
Sew your side seams up when you are finished decorating the sides like you want.
Now, to attach the oval top and bottom. Decorate the top the way you want it to look. Then sew a narrow stay stitch around the outside edge. I would add an additional skinny interfaced strip sewn on both sides like a belt for a handle. (sorry, I just thought of this) Pin the oval bottom on to the sewn sides clipping to ease it in. Sew around bottom, trim out any blulk. Do the same with the top. Now take a small piece of fabric and make a little rectangle to sew over where the zipper ends in the back. Stitch it on, avoiding the teeth of the zipper. (broken needles are the pits) Now sew up the two top and bottom lining pieces together in the same way, insert it into the bag wrong sides together and turn up the seam allowances to the inside. Hand stitch to the zipper seam line finish it up. Then, you can do a top stitch around the outside edges to hold it together right. And of course I would add a ribbon to the zipper pull to make it easier to use.