Hi DannyOceans,
If you are building a DIY mattress then I would read option #3 in post #15 here and the posts it links to so that you have realistic expectations about the learning curve and trial and error that may be involved in a DIY mattress. In most cases the most effective approach is to start with the specs of a local mattress that you have tested in person and have confirmed works well for you in terms of PPP as a reference point (assuming you know the specifics of all the materials and can buy the same layers and components individually) or to use a “standard” design that is suggested by one of the online members that sells component mattresses as your starting point and then you can make changes based on your actual experience instead of “theory at a distance”.
While I can certainly help with providing information about the quality of any materials you decide to use … there are too many unknowns, variables, and personal preferences involved for anyone to be able to give you meaningful suggestions based on “theory at a distance” or specs (either yours or a mattress) that can possibly be more effective than your own personal testing and experience (see mattress firmness/comfort levels in post #2 here).
I would start with a combination of materials and layers that seems to be similar to a mattress that you know you like or that works well for others that have the same body type and sleeping style and then once you have an initial configuration that you believe should work well for you then you can use your actual experience as a reference point to help you decide what to change from there.
Phoenix