The final category of manufacturers are the "do it yourself" manufacturers. Most of these are found online however some brick and mortar outlets make these available as well. They are growing in popularity and are very representative of the spirit of The Mattress Underground. These are a newer category of manufacturers and are often either smaller local and regional manufacturers who wish to broaden their market and have developed effective ways to custom build and ship their mattresses, or mattress manufacturers who are primarily online and more exclusively specialized in these mattresses. The online version in particular is growing in popularity as they can be ordered and easily shipped from any area of North America to any other.
They usually have several layers of material ... often latex or memory foam ... that can be put together in varying combinations and enclosed inside a zippered cover. They will often include wool quilting to comply with fire regulations or use more natural alternate methods. These layers and the cover can usually be shipped through UPS, Fedex, or other courier companies at a much lower cost than it would cost to ship a complete mattress with truck freight. They also usually offer the ability to make a "layer exchange" after a purchase where a single layer can be returned and exchanged for another to adjust the feel and qualities of the mattress and make it perfect for your needs. The length of time allowed and the costs involved in doing this vary from manufacturer to manufacturer, but are almost always far less than more typical "comfort exchanges" with their restrictive conditions and higher costs that are available through larger mass market outlets.
There are genuine advantages to this approach including quality of materials and the ability to custom build your mattress to a greater degree than a finished mattress from a store. They are typically very transparent in describing the exact materials that are in your mattress in terms of both the materials themselves and the specific qualities and "feel" of the materials you have chosen. They are usually very helpful and knowledgeable on the phone as well and offer differing ... but usually higher levels of service than many larger outlets since most of their customer interaction is online or on the phone.
The concept of layer exchanges can significantly reduce the cost of "making a mistake" whether it is from a store with restrictive exchange policies which represent a profit center for them or from a local manufacturer of a "complete mattress" purchased from out of your area where the entire mattress would need to be returned. These "do it yourself" constructions are particularly suitable for those who have done some reading and research in materials, quality, and methods of construction as well as some "field testing" in local stores, to get a clear sense of the mattress style and layer combinations that are appropriate for their needs. In these cases any "mistakes" in a choice of mattress will generally be small and easily addressed with a single layer exchange.
There are however a few disadvantages as well that you should be aware of all of which can easily be overcome with a little knowledge and field testing. The first of these is connected to their more "standardized" layering and in the lack of knowledge or understanding of many consumers who purchase them. Their slightly more limited choices of layer thickness and ILD can sometimes mean that these mattresses cannot be customized quite as well as a local manufacturer who has access to any thickness, ILD, and type of layering and may use different methods of construction, quilting, and ticking to produce a finished mattress that can be "customized" more accurately than a more standardized approach. Of course this is only a limitation in cases where the standardized approach, in combination with toppers and different types of quilting, do not include options that may be either important or necessary for a particular person.
A second difficulty with this approach is in the lack of information and knowledge of some consumers who purchase them in the belief that they are "easy to fix if I get it wrong". While this may often be true if you have done some research and field testing and know exactly what to change and which layer to change, there is sometimes so much confusion surrounding the effect of changing different layers and the effect it will have on the rest of the mattress that some consumers end up with a never ending search for the perfect layering pattern and never quite "get it right". While these circumstances are also more rare, they are common enough that it is well worth understanding exactly what you need both through some reading and research on this site or others, and through some field testing, before you decide to go in this direction. With the appropriate knowledge and testing though, they can represent tremendous value and have the ability to closely "duplicate" the feel of many if not most of the commercial mattresses that are sold in the "bricks and mortar" stores.
These outlets can make very good high value choices for anyone and are particularly helpful for those who may not have or know of a smaller manufacturer in their local area as they combine many of the benefits of local manufacturers with the benefits of online purchases.