Sleepsack pattern making

A lot of people ask me how I go about making patterns. In my opinion, the best way to start off (in order to get a detailed, custom-fit) is to make the pattern directly from a wrap of the slave or subject, in this case a complete head-to-toe mummification wrap. The objective isn't to create a bondage experience, but to create an envelope that records every contour of our subject, so THAT can be used to create a leather restraint that can provide a bondage experience. I use a layer of plastic wrap, followed by the duct-tape. It usually takes two to three rolls.
It's a particular challenge to make these larger pieces, like sleepsacks and f-suits with integrated hoods. Doing this sort of work made me realize why attached hoods aren't commercially available as a standard item: there are just too many variables in the way people are shaped, and making something that would fit someone "off-the-shelf" would be almost impossible. We are all unique.
I have probably mentioned this before, but I am always amazed at the variation between two models of the same height and weight. They could have vastly different proportions, including waist size, breast, hips and feet. The more fitted you want something to be, and the more picky you are about it, the more likely you will need to start with a wrap. I think of it like taking thousands of measurements all at the same time, and without using a ruler.

Note: You don't want the wrap to be too tight. Although duct-tape is pretty good at holding it's shape, if you make it tight, it will shrink after you remove your subject - resulting in a pattern that is too small. Keep it contoured and snug, but don't over do it. I try to use at least 2 layers of tape throughout. This also helps hold the shape.
Once the wrap is made, I mark seam lines on the duct-tape using a sharpie. Of course, I first cut the subject out, and re-tape the wrap closed. Unless I'm feeling mean. Then they stay in for this part...

These lines guide me when I cut apart the pieces and transfer them onto paper to make the pattern. Ideally, the left and right pattern pieces would be the same size and shape, but there is always variation between the sides. I use a process of averaging to make the pattern pieces symmetrical.

Where the seams go and the shapes of the pieces are guided by experience. In general, I try to keep the number of seams to a minimum. Certain shapes suggest themselves: when you try and flatten a complex shape like the shoulder, a single seam can help create the ball-like shape of the shoulder at the top of the arm. I try to pick lines that will be clean and pleasing to the eye.
At some point along the way, I'll make a drawing showing the piece, with seams, zips, closures and construction details in place. It helps me visualize all the patten pieces, how they relate to each other, and where I will cut them out of the hide. Finally, we can move on to the fun part: actually making the piece.