My parents have the Celebrity and I really like it, though it is a tad bit too firm. I'd like to recreate it or the Allura... here are the specs

 

http://www.tempurpedic.com/TEMPUR-HD-Collection/Tempur-Pedic-AlluraBed.asp

 

 

Comfort Layer	2" of highly-conforming quilted pillow-top TEMPUR-HD material
Support Layer	2.8" of TEMPUR® material
Base Layer	8.6" Dual AirFlow System™

 

I don't know if the pillow-top part of the pillow-top comfort layer is important at all but if it is how would i create the pillowtop part, an extra casing over that layer?

What type of foam is the base layer? There are basically two (so 4.3" each) with eggcrate on top of each.

What density/equivalent from somewhere like FDM would TEMPUR material or TEMPUR-HD be?

I think tempur HD is 7-8lb density.  The Tempur foam below that is 5.3lb.   The HD type foam is pretty hard to find, but you might want to search on google.  I know that Costco sells a mattress that has 2" of 7lb. over 3" (?) 5lb. over the base poly foam.   That is the closest to the Allura that I have seen.  Plus is cheaper and returnable.  Not sure what it is like though, since I have never tried it.

I know of at least 1 place that sells 6lb memory foam in 2".   The 5.3lb I got from foamorder came in at 5.9 density according to my calculations.

I liked the Allura myself in the showroom, and was tempted to buy it a couple of years ago.