Phoenix will chime in, but you may want to look at cotton/wool mattress pads. The wool will help cool things. Also with the 12 in 1, if you want to customize both sides of the mattress, you will need to cut the foam in half. There are posts about cutting foam (an electric carving knife helps).
I also had a question of the DIY variety, though I am not as ambitious as the gentleman that posted above.
I am looking at 3’ latex matress toppers being sold on Amazon by Dreamfoam Bedding. At about $400.00 apiece for each king-size topper, three or four of these toppers sandwiched together would run between $1200 and $1600.
That seems much much cheaper than a comparable mattress set being sold by Foam Sweet Foam or Flobeds which are also really just sandwiched layers of latex.
Couldn’t I just buy the layers from Amazon individually, then encase them in a king-size mattress cover and save myself a bunch of money?
Is there any reason not to do this and get the full mattress set instead?
Your idea is basically all the 12 in 1 is… a few layers of foam (in this case polyfoam) and a mattress cover. As a few others told me though, the real unknown is how all those mattress toppers would work together and if it would be comfortable for you. If they have a decent return policy you might be able to return/exchange the toppers if they don’t suit you.
Hi URSTech,
Congratulations on your new mattress first of all … you certainly made a good quality/value choice 
If you let them know you were a member here when you made your order they may still be able to add the pillow to your order.
Post #2 here has more about the many variables that can act together to affect the sleeping temperature of a mattress. While the top layer of foam can certainly make a difference … your mattress cover and quilting materials, your mattress protector, your sheets and bedding and your pyjamas will all have an effect and layers or materials that are closer to your skin will have a bigger effect than layers or materials that are further away.
The gels that are added to foams are either thermally conductive or phase changing materials and can have a temporary effect on conducting or storing heat away from the body but the effect tends to be temporary and when temperatures equalize then the insulating properties of the foam would once again become more apparent. There is more about gel materials in post #2 here and the posts it links to.
Airflow and moisture wicking are the most effective method of regulating temperature and in general terms latex (Talalay more than Dunlop) is the most breathable of all the foam materials. Natural fibers such as horsehair, wool, and cotton or viscose materials such as rayon or bamboo that can wick moisture away from the body and store it inside the fiber are more effective at regulating temperature than any foam. Synthetic fibers such as polyester don’t absorb moisture well and tend to maintain higher humidity levels closer to the body and sleep warmer.
The first step I would suggest before adding any layers that you may not need at all would be to do a little bit of experimentation with the layers in the 12 in 1 and then decide if you need to add anything else.
Phoenix
Hi Soldmyfortune,
You could yes … but the “trick” that may take some knowledge and experience along with some trial and error is in buying the “right” layers and firmness levels so that your mattress will work well for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). If you are considering designing your own mattress out of individual layers or components I would first read Option #3 in post #15 here and the other posts it links to so you have more realistic expectations of your initial success (before you start adding or changing layers) along with any savings you may or may not realize and the costs that may be involved if you make any mistakes and can’t exchange or return a layer. A good quality cover can also be a significant part of the feel and performance of a mattress … and the cost involved in the components that go into it.
Phoenix
So I am thinking about making my own platform bed. Regarding the slat spacing, I know the guides generally recommend no more than 3" between the slats. Is it possible for the slats to be too close together? What would the ideal slat spacing range for my polyfoam mattress be?
Hi URSTech,
This is a recommendation for mattresses that have a latex support core because latex is more flexible than polyfoam and can sink into gaps more easily over time. For a mattress that has a polyfoam support core then wider gaps would be fine although more slats and narrower gaps would still provide a more even and supportive surface.
As long as they provided good airflow then it would be fine. For example if you had 1x3 slats that were only an inch apart the airflow would still be fine but if you used 3 sheets of plywood that were divided in thirds (each @ 26" wide) with only an inch in between them then there would be little airflow under the mattress. The amount of flex under the mattress will depend on the design of the foundation and the type of wood (see post #3 here) and the thickness and width of the slats and the less flex the better. There are also some good DIY foundation or platform designs in the foundation post here (under the KD foundation section and the slatted platform bed section) that you can use as a reference.
Phoenix
URSTech, something to note if doing a diy platform frame with dimensional lumber from a home improvement store is type of wood. It can vary by region, but most typically 2x4’s (studs) and even 2x6’s are usually spf (spruce, pine, fir) variety. Depending on the store and area, check into larger boards like 2x10’s and 2x12’s - some even as small as 2x8’s will be a different type of wood. Southern yellow pine in most cases (syp) and is a stronger material. If you have the means and it’s worth the trouble to you, ripping your smaller boards (2x4’s and 2x6’s) from larger stock will give you better materials. Syp is still a ‘soft’ wood, but closer to a hardwood than the others with around 50% or more compressive and bending strength than either white pine or spruce and is also stronger (though not by as large a margin) than douglas fir. I think Phoenix linked to this in one of his posts, here is a listing of various woods and their properties. Southern yellow pine isn’t too far off from white oak in terms of strength. Hope this helps.
Thank you, that is a pretty great resource.
Will keep that in mind. I ran an FEA on the bedframe i designed though (using spruce structural properties), and its deflection point is at about 1020 lbs with a failure point at 1730 lbs. So I think between me my fiance and the mattress we should have a factor of safety around 3-4.
Anyhow sleeping with it on the floor tonight. Will see how hot it gets
The layers are very interesting. The medium and firm layers seem like regular foam you might find in a couch seat cushion. The soft layer is almost tacky and while not memory foam feels like its almost a hybrid of MF and the Polyfoam.
Will be testing it out over the next few weeks and let yall know how I like it!
Thanks a bunch for all the advice.
Because polyfoam mattresses are more forgiving in their needs, it may be cheaper/easier to buy a bed. You should check out the foundation thread.
Hehe, well individuals like me don’t always do whats easier just because they actually enjoy the design and construction process 
I have access to pretty much free material though, so this will undoubtedly be cheaper than any of my alternatives.
Just wanted to report in and say thanks for all the assistance.
The 12 in 1 mattress is great. I had some issues early on with some slight lower back tenseness but eventually figures out I had it set too “soft”. swapped up the layers so its more of a medium firmness, no back pains anymore and sleeping comfortably through the night!
No smells to speak of other than a very light odor early on. Quality of the cover seems very good too.
Thanks all!
Hi URSTech, that’s great. Glad your 12 in 1 is working out so well for you. Being able to swap layers around for fine tuning can be a real blessing. Sounds like you found the right combination. Since you’ve slept on your mattress, I’m guessing you got your bed sorted out as well. Did you end up building your own? If so, what did you decide to make it out of?
I’m still in the process of building mine, need a few more materials and need the weather to cooperate. Had a couple weeks without rain but had some other work that needed done and had to take advantage of the dry weather. Back to rain for the next week or so with only maybe a day or two break. Unfortunately no garage or workshop lol - anyone need rain? I’d be happy to send the clouds their way
Hi URSTech,
Thanks for the update … and it’s great to see that things are working out well for you
I’m also curious about the bed you were planning to build as well.
Phoenix
I went ahead and built a simple platform bed out of cedar they were selling at a local Lowes. Figured it smelled nice and the extra bug resistance couldn’t be bad right? Plus it cost about the same as their pine. I am using some reclaimed brazilian cherry flooring for the backboard (its really the only part of the bed you see) and its turning out beautifully. Will post some pics when its done!
I built a platform bed out of some cedar I found at a local lowes (think they use it for decking). The cedar cost about the same as pine and smelled nice too, so I figured why not. Cedar is softer wood, but I designed enough bracing into the frame that I’m not really worried about that. I am making the headboard out of reclaimed brazilian cherry flooring (really beautiful wood), quite pleased with how its turning out.
Also making a dinner table (again out of the brazilian cherry) and a marble top chess table, so I’m kinda juggling a few projects. Plus my fiancee and I just nailed down a date in October for our wedding… So a lot going on right now! Will post some pics of the bed when its all finished.
URSTech, sounds good. I think most of the notable differences with softer cedar, aside from the hardness (how much pressure does it take to leave an impression or nick), is when it’s laid flat. It’s pretty sturdy with loads applied to the end (like a bed frame leg, upright). Sounds like it’s really coming together. Also, congrats on setting the date.
Hi URSTech,
I’ll add my congratulations on your engagement as well
I hope you have a chance to post some pictures of your projects (or at least the bed) on the forum when they’re done.
Phoenix
One Thing I do like about cedar is that it tends to be much more dimensionally stable. Very easy to find nice straight boards with no cupping/warping/checking. That also means the frame will not move much over the seasons, which tends to be an issue in our humid summers.