Merino sleep sacks are a really great thing for babies, but who wants to spend $100 on one? Goodwill to the rescue! Look for the largest men's merino sweater you can find (at least XL), preferably with the fewest holes (let's be real -- the most likely reason a beautiful Jos. A. Bank sweater will be donated to Goodwill is because it has holes in it). Wash it in cold water on gentle cycle and dry flat. Cut apart along all seams.
I used the Mamma Can Do It sleep sack pattern, but I'm sure most any sleep sack pattern will work. I found it easiest to trace the back pattern piece (which is supposed to be cut on the fold) twice and make it one whole piece, to cut out from the back of the sweater. The tricky part is dealing with the ribbed part of the sweater at the bottom, since it stretches differently from the rest of the sweater. I experimented a bit, ignoring the rounded part of the pattern and just taking it to the fullest point and then straight down at the sides, but I'm not completely satisfied. The most important thing is to make the front & back of the sleep sack the same. Cut the two front pattern pieces from the front of the sweater, and cut the facings and zipper tab from the sleeves.
[If you have any interest in doll clothing, you can use the ribbed cuffs of the sleeves to make a pair of doll socks (the ribbed cuff makes the leg part of the sock and the rest is the foot part). Cut out each one in a U shape approx. 4.5" wide and 5.5" tall. Fold in half (right sides together) and serge the edges. Tuck in serger tails and turn right side out.]
Save some of the scraps and unravel a thread to use to mend the holes. Hold each piece up to the light to see if there are any weak spots (future holes) that might need Fray-Check.
Sew the sleep sack according the the pattern directions. Just for fun, I cut out the Jos. A. Bank tag and sewed it into the sleep sack to show that it is 100% merino wool. On a couple of them, I used one of my "Made with love by Grandma" tags to cover up the worst hole.
