These quilts turned out to be about 21 ounces, with 13 ounces of that being down. This resulted in a loft of about 2.5-3", which means they should be toasty down to 20 degrees. The quilt design uses a karo-step baffle. Note that these are "quilts", which mean they lay flat, and then can cinch together at the top and bottom using elastic shock cord, and have 6 buckles to hold the quilt together at the seam. The idea is to have the seam underneath you while you sleep when it's really cold.

This instructable will walk you through what supplies to order, how to adjust measurements to customize for you, how to measure and mark the baffles, sew and stuff the quilt. The total time to complete this project once you get the supplies and have decided on your measurements is about 8-12 hours, depending on your level of experience.

I watched and re-watched Dubber's excellent video on how to make your own quilt - I highly recommend it!

Understanding a karo-step baffle is a little tricky if you haven't done it before - this illustration (image 2, figure 4), is how it finally made sense to me.

If all of these feels overwhelming, I would recommend buying a bag from Englightened Equipment. The only reason I didn't was because they had a 5-7 week wait period on ordering bags, and I needed mine within 4 weeks. Also, I'm a quilter, so enjoyed learning something new!

Step 1: Measurements and Supplies

First you have to decide on the quilt dimensions you need.

Width - I decided just use the full width of the yardage I bought, which is very close to 60" - the finished quilts are about 57" wide at the top, through the hip. This seems to be sufficient (although snug) for my husband, who is 6'0". It's plenty for me (a 5'6" woman). The footbox is 40". I decided to start my taper for the footbox about 1/3 from the bottom. If you need wider than 57" finished, you will need to buy extra yardage to sew an extension to the width of the yardage you get.

Height: General rule of thumb is your height + 6". Then you need to add at least 1" for seam allowance. I would recommend your height + 8 or 9". It sucks if your quilt is too short. An extra inch of room feels luxurious. Note these quilts are designed to stop just below your chin. You will need a hat or hood to keep your head warm when it's really cold.

Loft Height: This is where you need to decide what temperature rating you want this quilt to have. You could use this design to make a night lightweight summer bag: make the baffle walls shorter and add less down. Or you can make the baffle walls higher and add more down for a warmer quilt. Here's a rough guide:

1.5" = 40 degrees
2" = 30 degrees
2.5" = 20 degrees
3" = 10 degrees

Note that different people sleep differently. Most women, for example, sleep 10 colder than men. So that means that if you have a 20 degree bag, it may only keep you warm to 30 degrees if you are a woman. This is true for some men too. You can always add layers while you sleep if you find yourself getting too cold, or open up your quilt if you are getting too hot.

So how high to make the baffle walls? I like Dubber's method that if you cut them to the height you want (so if you want a 20 degree bag, cut them 2.5" wide), then with seam allowances, they actually turn out to be 2", which leads to that "over stuffing" look, which I like. Because, cozy.

Supplies

A note about supplies: I put some links in here to the supplies I ordered. Do your own research, there are other online vendors that sell materials that I'm sure work just as well. I have no affiliation with Ripstop by the Roll, but found their customer service to be great and personal, and the supplies I ordered to come quickly. I am just a satisfied customer.

Here's what you need:

A sewing machine - don't have one? Beg your friend to borrow one! Preferably one who is a quilter and also has a quilter's cutting board and rotary cutter and is willing to show you how to use it to help you cut your baffle walls.
Sharp needles - the ones I used are pictured in this step - 60/8 sized needles
Dress maker's pins (sometimes called silk pins?)
At least 200 yards of 100% polyester thread - DO NOT USE COTTON. Cotton will fall apart on you in the woods after extended use. And then there will be crying.
A long measuring tape - at least 120" long
A roll of masking tape
Sharp scissors
A fabric chalk pencil or Fine point Sharpie (I found the sharpie MUCH easier to work with, but it does show through a bit on the other side)
5 yards of Calendared ripstop nylon. You want to select calendared. This means one side of the fabric has been finished to create a smooth coat on one side of the fabric, which means you will lose less down and will (possibly?) be a little more moisture proof. If you want the top and bottom to be different colors (AKA fancy), then you should order 3 yards of each color, because you can't order half yards). If you like the two-tone top like I did with the purple/pink and pink/orange bags, that was 1 yard of the middle color, and about 1.5 yards of the other color. You will need to cut the 1.5 yard color in half and sewing it to the middle color before doing all the other measurements.
1 yard no seeum mesh. The color doesn't really matter here. You won't see it. Cut and folded is fine.
At least 12' of 1/8" Shock cord
18" of 5/8" grossgrain ribbon.
4 mini cordlocks
6 Center Release buckles (5/8" webbing width)
Goose Down - the amount depends on how warm you want your quilt to be. I used 12 ounces of Hyperdry 850 fp goose down from Ripstop by the Roll. I found they were generous in what they sent me, and ended up being able to get close to 13 ounces in each bag. This is definitely the most expensive part of making these sleeping bags. Order your down from a reputable place. You may be tempted by lower prices somewhere, but there is a reason the more expensive down is expensive. It's better. People have strong opinions that goose down performs better than duck down as well. IMHO, if you're going through all this trouble to make your own bag, do it right.

Step 2: Cut and Measure

Phew, you got all those supplies, and now you're ready to get started! This is arguably the most important step. The more accurate you are with your measurements and markings, the better the quilt will line up.

1. Cut out the strips of no seeum mesh for the baffle walls. If you want 2" baffles, cut long strips 2" wide - this is much easier if you have a quilter's cutting board and rotary cutter. If you are making 10" x 12" baffle boxes like I did, you will need:

36 2" x 5" pieces of no-seeum mesh - make a few extra, it won't hurt, you might need them.
36 2" x 6" pieces of no-seeum mesh.

2. Tape down the top and bottom of the ripstop nylon to the floor - you need a big flat space to work! Important: make sure you have the shiny side UP. This is the wrong side. When your quilt is done, you want that shiny side on the inside.

Use your tape measure to mark out the 10" lines by lining up the tape measure across the width, and marking out 10" notches. Do this at the top, middle and bottom.
Move your tape measure to the long way, line them up along the 10" lines you just notched out, and measure the overall length - remember, you probably want it to be your height + 9". So if you're 6" tall, you want the pieces to be 81" tall.
Use this tape measure to mark out the baffles for the 12" side of the boxes along each of the 10" lines. This means you will leave a gap for the first 6", then mark a line for the next 6", and repeat until you hit the end of the quilt. Think this through first - if you are making a 76" length quilt, you may want to start the first baffle 7.5" down so you even out the excess - because if your length isn't evenly divisible by 12, you have to decide how to divide up the remainder. Sorry, you're going to have to do some math :/ Also, I mark out the 12" blocks (so do a notch 3" into the 6" of blank space) to make the next step more accurate. You should have 5 columns marked out now (assuming you stuck with the 60" width)
Once you hit the end, move the tape measure width-wise. Line it up along then 12" block marks you made in the last step (the small notch in the middle of the 6" spans of free space). You are marking the 10" side of the baffle walls, so make that mark 2.5" in, draw a 5" line, then skip 5". Repeat until you hit the end. Depending on your length, you should have 5-6 rows marked out.

3. Mark out the foot box taper cut - this is easy now that you have made all these marks. Line up your tape measure 1/2" inside the first 10" column and mark a line to the about 48-50" down - it doesn't really matter where you start the foot box taper, just do it consistently. I lined mine up to be about knee-height. The total width at the bottom should be 41" at this point.

4. Cut the length and the foot taper.

5. Repeat this for the bottom. Again, make sure the shiny side is UP.

6. On the TOP piece only, use masking tape to tape the no seeum mesh baffle walls you created in step 1 to tape the mesh to the lines you drew. This is optional, but I found it was much easier to sew the mesh to the nylon with the tape stabilizing the mesh. Obviously, match the 6" pieces you cut to your 6" lines, the 5" pieces with the 5" lines you drew.

Step 3: Hem Outer Edges, Sew Baffles to Top

Now you're ready to sew! Make sure you test out working with the nylon with a scrap piece first, and adjust the tension. Working with these materials is like trying to sew butterfly wings to pantyhose, so it's hard to get the tension right. Even after I worked on it for a while, it never got as "clean" a seam as I usually like it when I quilt with cotton fabrics, but, I'm guessing it's just part of working with this material with a home-grade sewing machine.

1. Sew a 1/2" hem around the exterior of both the top and the bottom.

2. Sew each baffle wall along the line you drew. You are working with the underside of the TOP quilt now.

3. Remove the tape, cut any excess string.

Step 4: Step 4: Add the Center Release Buckles to the Top of the Quilt

I added 6 buckles to the seam by adding them to the top of the quilt using 2" strips of Grosgrain ribbon.

Pin all the female sides of the clip to one side, evenly spaced. I didn't measure here, just added them where I thought they made sense. Make sure the top and bottom buckles are about 2 inches up from the bottom to leave space for the shock cord canal. Also make sure the clips are all facing the same way.
Fold the quilt in half, length-wise, and line up the male clips to clip into the female clips you just positioned, and pin them in place. Do a reality check here - did you line them up so they will clip and unclip in a way that makes sense?
Sew these in place at least twice. These will take a lot of tugging, so you want them secure.

Step 5: Sew the Top Quilt Baffles to the Bottom

This is the trickiest step. I laid the bottom of the quilt, with the shiny side UP on the floor, then laid the top of the quilt on top of it with the baffles I had sewn in on the inside. Unfold the top half, and line up the top baffles with the lines on your bottom nylon. Tape these. You won't need to tape the rest of them, but this first one is nice to have taped.

Sew the mesh to the bottom along the line you drew. Do all the baffles in the middle column.

Now this is the tricky part, and will require some tugging, but you'll figure it out. You will line up the next line that is perpendicular to the column you just sewed. Sew the mesh to the bottom along the line you drew on the bottom. Start at the top of the line and move down towards the row you just sewed.

Repeat until you've done all the baffles. Keep checking your work - after each row or column hold it up, make sure you're still on the right path.

Step 6: Seal the Edges, Sew in the Shock Cords

Now you've got the top and bottom quilted together, and you're ready to seal the edges! If you were careful with your measurements, you the edges should more or less line up. If they are a little off, it's okay, we won't tell.

Sew a straight seam along the top and bottom, sewing the two pieces together. Cut a length of shock cord for the top and the bottom, and thread it through. Add a knot and a cord stop to each end. Then sew and extra seam about an inch below the first one to make a little canal for the shock cord. Make sure you don't sew the shock cord to the quilt - you need it to move freely.

Sew the long edges together, but leave a 10" gap in one side wall to leave space for stuffing.

Congrats! You've hit the home stretch!

Step 7: Stuff the Bag With Down

I don't have any pictures of this, but if you watch Dubber's video, he's got good footage of this step. I used his method of standing in my shower with the curtain closed to the keep the down in. You will feel like you are in the Upside Down.

Basically, you need to contain the flying down and try and get it all in the bag. Try and move the down around and get some into each baffle. The nice part about the Karo step baffle you worked so hard to make is that the down can be redistributed after construction. But it is easier to move it around while you're stuffing it.

I weighed my bag before and after stuff so I knew exactly how much down I got inside, if you want to do that as well.

Step 8: Close the Bag, Have a Beer

Now you just need to close the bag by sewing a seam along the 10" opening you left where you were stuffing the bag.
YOU DID IT! You are amazing, and deserve a beer. Or at least a big piece of chocolate cake.

Happy Trails.