I noticed that you registered with your email as your username which means that automated spambots can harvest your email and add you to their spam lists. If you’d like I can remove the @ and the domain after it and change your username to just jazminlee35 (or any username you wish).
If you are attracted to the idea of designing and building your own mattress out of separate components and a separate cover then the first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
If you decide to take on the challenge then I would either use the specs (if they are available) of a mattress that you have tested and confirmed is a good match for you in terms of PPP as a reference point or use a “bottom up” approach (see post #2 here).
@GenericMattressShopper,
In “theory” a support core that used two 3" layers of latex that were both the same type and firmness of latex as a single 6" core could feel slightly softer but in “real life” I don’t think that most people would notice much if any difference in how they feel (see post #2 here).
Phoenix