This is a simple little sewing project for people to work on, as well as a nice introduction to self-made specialist kit. What's good about this design/concept is that you can easily expand on it, make it heavyweight or super lightweight, add more functionality or less. It can also be made out of any kind of material, cheap or expensive, and on any kind of sewing machine, or could even be hand sewn.
The basic concept is a lightweight insulated mat cover for your fragile inflatable mattress, the kind of thing you'd take both on an expedition, where you will generally have a two mat system or for general camping. It can also be used as a stand-alone sleeping mat or even split into two separate mats for use as a tent underlay, for example, or in an emergency for two sleepers.
This cover is designed to protect the air mat from damage, both in transit and while being slept on, both from above and below, as well as add extra comfort and redundancy, being a winter weight mat in its own right (so if your air mat springs a leak, you can still sleep).
The mat can also connect to another mat of the same design via some form of toggle, button or clip. These clip points can also be used to secure the mat to a rope or portaledge when on an exposed bivvy This allows you to better cover the ground, important when camping on snow or using a two-bag system.
The idea of the mat comes from a new discontinued expedition mat cover made once upon a time by Exped (two of these were used on the first North Pole winter expedition). I expect the Exped mat was eventually discontinued due to no one really understanding what it was really for (a common issue with great kit). Never the less, such a mat is very easy to make yourself.
All you will need for this project is a standard sewing machine, some good quality thread (1oz to 4oz bonded polyester thread), size 70 needles, some quality scissors, pins or medium fold back clips to join up your fabrics before sewing. You'll also need some space to lay out your fabrics and a large ruler or straight edge, and something to mark your cloth (pen or tailor's chalk).
Fabric and materials
For this project, you'll need the following parts:
2 sheets of foam: You're going to sandwich your air mat between 2 thin EVA mats (closed-cell foam). These can be any thickness, but for portability and expedition use, I'd go for something between 3 mm and 6 mm, with 6 mm being best for expedition use, as this gives you a 12 mm mat, the minimum for camping on snow (if your air mat springs a leak). Of course, you could always vary the thickness, and have a 3 mm mat matched with a 9 mm mat, so you can use either mat alone. You can buy EVA foam from Cosplay suppliers (people make shields and Gandalf's underpants out of the stuff), in 2 metre by 1 metre rolls in thickness from 1 mm to 10 mm. Get CF65 foam as CF100 probably too stiff.
Shell material: This depends on what you're intended purpose will be, and the length of fabric will depend on the width of the fabric you use. Both top and bottom can be the same, or you can use a waterproof bottom fabric, such as 36g silicone nylon, or heavy-duty PU or neoprene nylon, and more comfortable, next to skin fabric on top, like 55g nylon Nylon taffeta. If you wanted to make a very tough bedroll, the kind of thing you'd carry in a van, then you could go for 200 denier Cordura (or copy texturised nylon), or even heavy-duty canvas (polycotton).
Mating Buckles: I'd go for 9 mm tape threaded through tape toggles, sewing each to act as both male or female. These will also double up as clip points, so make sure they're sewn in well to the seam.
Webbing and buckles: Sew in a single or double strap using 20 mm Fastex buckles (get ITW Nexus buckles, as they tend to break less when you stand on them), or make velcro straps.
Closure: You need some way to close the bottom of the mat. This can be either a zipper or velcro, with velcro being much easier to do. If using velcro, add tabs on either side to make it easier to pull apart.
The basic idea is to cut out two oblongs of fabric to create the top and bottom of the cover. Into this, you want to sew in top and bottom sleeves to hold the EVA foam in place. When measuring out the size, allow yourself plenty of extra fabric, so you don't end up making it too small for your air mat. You will also sew in the closure system (ideally velcro), and the toggles and straps into one side, beefing up the stitching on these high loads areas (make sure you sew them so they'll be on the outside once you sew up the cover!). Sew the top and sides using a flat felled seam (practice this first with some cut-offs), making sure all your toggles and straps are on the outside.
Taking it further
You can sew the mats with a little more space and insert open-cell foam rather than an air mat. This might create a more robust bedroll style mat.
If you use 3 mm or 6 mm foam, you can cut it up into back sized sections, then tape them together, so you can concertina them up and stick them in your pack.
One side of the mat could be made from high vis material and even feature strips of reflective material, so it could be as a rescue panel.
You can sew a chessboard design into the mat using squares of fabric, or just mark it with pen.
Sew a strip of reflective tape on the outside end of the mat, so when it's rolled up and put on a pack, you have a reflective surface.
It would be easy to modify this design so, adding in extra buckles and seams so that it could be folded in such as way as to make it into a chair.
One layer of mat cover could be bellowed, so it could hold a sleeping bag, meaning both bag and mats could be rolled up like a bedroll, ideal for casual camping.
It would be possible if using heavyweight materials on one side to add grab loops so the mat could be used (look up British Army emergency hammock).