I made my own coat pattern by tracing a jacket I already had onto a flannel sheet, adding seam allowances, and cutting out my pattern pieces. Then I basted the flannel pieces together for a fitting, and ended up changing the pattern around... a LOT.
When I was happy with the fit, I cut my pattern pieces out of the fashion fabric and the lining. I used a 1/4" seam allowance for the khaki, and 5/8 for the fleece, so that the lining would finish a bit smaller than the shell. I opened the fleece seams flat, zigzagged them so that they would stay flat, and trimmed them close to reduce bulk.
The cuff ruffles were sewn into the seam where the jacket meets the lining. I folded the edge of the collar/lapel ruffle under, and topstitched it down. It goes all the way around the back of the jacket. I decided not to topstitch the rest of the front or the hem, and instead understitched the facing and lining to the seam allowances to keep it from rolling to the right side.
I used some old wooden buttons that I had saved from a worn-out coat. I didn't want them pulling through or distorting the fabric, so I backed them with another button on the other side. The button loops were actually pieces of a shoelace!
The earmuffs were actually the trickiest part. I cut two circles out of each fabric, making the fleece circles smaller than the khaki. Then I sewed the edges, right sides together, all the way around. I had to stretch the fleece a bit to make it fit. Then I cut a slit in the fleece, turned the circle right-side out, and used a hand needle to run elastic thread all around the stitching line, weaving it in and out of my machine stitches. I measured my head and made plain straps out of the khaki fabric, and did not elasticize them, although I could have if I wanted to. They stayed up fine without elastic during the safety-pin fitting, so I left them as they were. Next, I used the slit to flatten out the fleece and sew the straps to the fleece only, so that the stitches which connect the strap to the ear covering are not visible from the outside. Then, I whip-stitched the slit closed, and hand-sewed a second fleece circle to the inside of each earpiece, turning the edges under as I went, to cover up the strap connection and the slit that I used for turning. When I'm wearing them, the lower strap is completely hidden by my hair.
The handwarmer muff was fairly easy, just two rectangles, a thick piece of batting, and two ruffles sewn into the long seams. The hardest part was probably pulling all those gathering threads, since I don't have a ruffler foot for my sewing machine!